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 38 to 42.

For many American university students, the weeklong spring break holiday means an endless party on a sunny beach in Florida or Mexico. In Panama City Beach, Florida, a city with a permanent population of around 36,000, more than half a million university students arrive during the month of March to play and party, making it the number one spring break destination in the United States. A weeklong drinking binge is not for anyone, however, and a growing number of American university students have found a way to make spring break matter. For them, joining or leading a group of volunteers to travel locally or internationally and work to show problems such as poverty, homelessness, or environmental damage makes spring break a unique learning experience that university students can feel good about. Students who participate in alternative spring break projects find them very rewarding. While most university students have to get their degrees before they can start helping people, student volunteers are able to help people now. On the other hand, the accommodations are far from glamorous. Students often sleep on the floor of a school or spend the week camping in tents. But students only pay around $250 for meals and transportation, which is much less than some of their peers spend to travel to more traditional spring break hotspots.

Alternative spring break trips appear to be growing in popularity at universities across the United States. Students cite a number of reason for participating. Some appreciate the opportunity to socialize and meet new friends. Others want to exercise their beliefs about people’s obligation to serve humanity and make the world a better place. Whatever their reason, these students have discovered something that gives them rich rewards along with a break from school work

The word “them” in paragraph 1 refers to _______.