What is the topic sentence of the following text? “Initiating conversations with those around you can create some of the most unexpected friendships. The conversation can start in a non-personal way such as discussing lectures or reading assignments, and can lead to meeting for coffee outside of the classroom. It is also helpful to get to know your classmates so that you can find a study partner or have someone you can reach out to for information if you have to miss a class. In classes held in large lecture halls, it is helpful to know a few people, so you don’t feel lost in the crowd.”
选项：

A:Initiating conversations with those around you can create some of the most unexpected friendships.
B:In classes held in large lecture halls, it is helpful to know a few people, so you don’t feel lost in the crowd.
C:The conversation can start in a non-personal way such as discussing lectures or reading assignments, and can lead to meeting for coffee outside of the classroom.
D:It is also helpful to get to know your classmates so that you can find a study partner or have someone you can reach out to for information if you have to miss a class.