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 from 39 to 43.

What makes people give money to charity? One reason is altruism, the unselfish desire to help other people and make the world a better place. For example, religious institutions receive the highest percentage of donations in the United States. Colleges and universities often receive gifts from successful graduates who want to widen educational opportunities for other students or support research on an issue they feel is important. Hospital and medical research organizations are often supported by donors who have been affected by a medical problem, either directly or through the experience of family members or friends. Many donors give to causes that have touched them personally in some way. Charitable gifts can also be made for reasons involving personal interest. Under U.S tax law, an individual does not have to pay income tax on money that is donated to charity. For extremely wealthy individuals, this can mean millions of dollars they do not have to pay in taxes to the government. In addition to tax benefits, donors often receive favorable publicity for making donations, and they have an opportunity to influence the world around them. For instance, new buildings at colleges and universities are often named after important donors, which means that they will be remembered for their generosity for many years to come.

(Adapted from Macmillan Exams, Roy Norris, Ready for First, 3rd Editor)

The word "they" in paragraph 1 refers to ________.