Given the task definition, example input & output, solve the new input case.
In this task, you're given five sentences, numbered 1 through 5, and two options a and b for possible titles for the story. Your job is to choose the title that better fits the story. Indicate your choice by 'a' or 'b'.
Example: Sentence 1: Marcus needed clothing for a business casual event. Sentence 2: All of his clothes were either too formal or too casual. Sentence 3: He decided to buy a pair of khakis. Sentence 4: The pair he bought fit him perfectly. Sentence 5: Marcus was happy to have the right clothes for the event. Choices: a. Marcus Buys Khakis. b. Marcus Works.
Output: a
Marcus's reasons for buying khakis is established, followed by his purchase of them and reaction.

New input case for you: Sentence 1: Wallace was working with his team for his college chemistry lab. Sentence 2: They needed to create a solution using a certain amount of chemicals. Sentence 3: Wallace and his team carefully read the instructions. Sentence 4: Unfortunately, one of the team members wasn't fully paying attention. Sentence 5: Their solution started pouring out, making a mess of their work table. Choices: a. Susie's Intense Summer. b. Chemistry.
Output:
b