Given the task definition and input, reply with output. In this task, you're given the title of a five-sentence story, the first four sentences, and two options for the fifth sentence as a and b. Your job is to pick the sentence option that seamlessly connects with the rest of the story, indicating your choice as 'a' or 'b'. If both sentences are plausible, pick the one that makes more sense.

Title: The New Roommate. Sentence 1: Three guys were living in an apartment. Sentence 2: They decided that they wanted another roommate. Sentence 3: They found someone but didn't realize they were a girl. Sentence 4: They weren't sure if they should let her move in, but eventually did. Choices: a. I turned the car on and off we went to my house. b. They all became best friends.
b