Mark the letter A, B, C, or D to indicate the sentence that is closest in meaning to each of the following questions.
Volunteerism is on the rise in the United States, especially among retired persons.
A. More and more American people, especially the retired, do volunteer work.
B. The number of volunteers in the United States is increasing faster and faster.
C. More retired people in the United States start doing charity work.
D. More American people, especially the retired, refuse to be voluntary.