Teacher: In this task, you're given four sentences of a story written in natural language. The given story is not complete and your job is to complete the story by selecting one of the sentence choices from (A) and (B), such that the story sounds fully coherent.
Teacher: Now, understand the problem? If you are still confused, see the following example:
Sentence1: Rick grew up in a troubled household. Sentence2: He never found good support in family, and turned to gangs. Sentence3: It wasn't long before Rick got shot in a robbery. Sentence4: The incident caused him to turn a new leaf. 
 (A) He is happy now. (B) He joined a gang.
Solution: A
Reason: As mentioned in fourth sentence, the incident turned a new leaf to Rick's life; so, he must be happy now.

Now, solve this instance: Sentence1: A scientist discovers that there is a disease beginning to spread. Sentence2: He works on a cure for the disease in his lab. Sentence3: Other scientists gather to help him with his work. Sentence4: Several weeks go by and they manage to develop a cure. 
 (A) They feel foolish for having done so. (B) They save the world.
Student:

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