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: Help. Sentence 1: Anna's little brother needed help with his math homework. Sentence 2: But Anna's mom worked a lot and had little time to help him. Sentence 3: So Anna took it on herself. Sentence 4: Every day she tutored him. Choices: a. Soon he had really improved in math! b. Unfortunately Tom was late to work anyway.
a