This question is missing the excerpt and one of the options. I've found the excerpt and the missing option online. It is as follows:
Read the excerpt from Enrique's Journey.
Moreover, the Mara Salvatrucha street gangsters, some deported from Los Angeles, always prowl the train tops looking for sleepers. Many MS gangsters settle in Chiapas after committing crimes in the United States and being expelled to their home countries in Central America. The police in Chiapas are more forgiving of gangs than those in El Salvador or Honduras.
[...]
E. It supports the idea that the gangsters are involved in criminal activities.
Answer:
The meaning of the underlined word, prowl, support the author's purpose in this excerpt because:
C. It indicates that the gangsters are looking for vulnerable people.
E. It supports the idea that the gangsters are involved in criminal activities.
Explanation:
The verb to prowl refers to someone moving around stealthily with the purpose of finding a prey. When the author chose that verb to describe the way the gangsters act, she wanted to convey the idea that they prey on other people, that they are involved in crimes. Gangsters look for vulnerable people on train tops, according to the excerpt, certainly with the purpose of robbing them. It is as if they are predators, prowling around a forest to find their prey.
