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 input: 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.
Example output: a
Example explanation: Marcus's reasons for buying khakis is established, followed by his purchase of them and reaction.
Q: Sentence 1: Anna was hiking with her family. Sentence 2: Suddenly she tripped on a tree root. Sentence 3: She fell into a patch of poison ivy! Sentence 4: Anna was miserable as she suffered from the plant's effects. Sentence 5: Her family felt very badly for her. Choices: a. Sting. b. Fall.
A:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
b