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: School. Sentence 1: Tom was struggling in school. Sentence 2: He decided to hire a tutor. Sentence 3: He found the tutor very useful. Sentence 4: His grades soon improved. Choices: a. But her friend totally ignored her. b. Tom became very happy with his academic performance.

b