Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 25 to 29. Fill in the appropriate word in question 28

  Left- handers are the odd ones out. Sure, lefties (25) _________ up about 10 percent of the population,

but, frankly, it seems like society has forgotten about them. Just consider all of the right-handed gadgets, awkwardly designed desks, and cooking tools that fit comfortably only in your right hand.

  What (26) _________ someone to become a southpaw? Scientists aren't exactly sure, but research points to a complex (27) _________ between senes and environment. While no exact set of “leftie genes” have been discovered, people who dominantly use their left hands do have more left-handed family members. And researchers have found different brain wirings in righties vs. lefties. But no matter (28) ________ it is that drives someone to use their antipodal paw, science has also uncovered a particular set of personality traits that left-handed people tend to have. So for all of you lefties, leftie- loving righties, and ambidextrous folks out there - it’s time to brush up on your left-handed knowledge and help (29) ________an end to leftie discrimination once and for all.

A. what

B. who

C. which

D. that