Read the following passage and mark the letter A, B, C ,or D on your answer sheet to indicate the correct answer for each of the questions.

Many ants forage across the countryside in large numbers and undertake mass migrations; these activities proceed because one ant lays a trail on the ground for the others to follow. As a worker ant returns home after finding a source of food, it marks the route by intermittently touching its stinger to the ground and depositing a tiny amount of trail pheromone – a mixture of chemicals that delivers diverse messages as the context changes.

These trails incorporate no directional information and may be followed by other ants in either direction.Unlike some other messages, such as the one arising from a dead ant, a food trail has to be kept secret from members of other species. It is not surprising then that ant species use a wide variety of compounds as trail pheromones. Ants can be extremely sensitive to these signals. Investigators working with the trail pheromone of the leafcutter ant Atta texana calculated that one milligram of this substance would suffice to lead a column of ants three times around Earth.

The vapor of the evaporating pheromone over the trail guides an ant along the way, and the ant detects this signal with receptors in its antennae. A trail pheromone will evaporate to furnish the highest concentration of vapor right over the trail, in what is called a vapor space. In following the trail, the ant moves to the right and left, oscillating from side to side across the line of the trail itself, bringing first one and then the other antenna into the vapor space. As the ant moves to the right, its left antenna arrives in the vapor space. The signal it receives causes it to swing to the left, and the ant then pursues this new course until its right antenna reaches the vapor space. It then swings back to the right, and so weaves back and forth down the trail.

The author mentions the trail pheromone of the leafcutter ant in line 11 to point out

A. how little pheromone is needed to mark a trail  

B. the different types of pheromones ants can produce  

C. a type of ant that is common in many parts of the world  

D. that certain ants can produce up to one milligram of pheromone

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.

Rachel Carson was born in 1907 inSpringsdale,Pennsylvania. She studied biology at college and zoology atJohnsHopkinsUniversity, where she received her master’s degree in 1933. In 1936, she was hired by the U.S. Fish and Wildlife Service, where she worked most of her life.

Carson’s first book, Under the Sea Wind, was published in 1941. It received excellent reviews, but sales were poor until it was reissued in 1952. In that year she published The Sea Around Us, which provided a fascinating look beneath the ocean’s surface, emphasizing human history as well as geology and marine biology. Her imagery and language had a poetic quality.Carson consulted no less than 1,000 printed sources. She had voluminous correspondence and frequent discussions with experts in the field. However, she always realized the limitations of her nontechnical readers.

In 1962, Carsonpublished Silent Spring, a book that sparked considerable controversy. It proved how much harm was done by the uncontrolled, reckless use of insecticides. She detailed how they poison the food supply of animals, kill birds and fish, and contaminate human food. At the time, spokesmen for the chemical industry mounted personal attacks against Carson and issued propaganda to indicate that her findings were flawed. However, her work was proved by a 1963 report of the President’s Science Advisory Committee.

Which of the following was NOT mentioned in the passage as a source of information for The Sea Around Us?

A. printed matter

B. talks with experts

C. a research expedition

D. letters from scientists