Given the task definition, example input & output, solve the new input case.
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.
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.
Output: A
As mentioned in fourth sentence, the incident turned a new leaf to Rick's life; so, he must be happy now.

New input case for you: Sentence1: Anna has lost twenty pound in three months. Sentence2: Her friends aren't sure what her secret is. Sentence3: Last week they decided to ask her. Sentence4: She said she was working out and eating better. 
 (A) Anna's friends thought her methods were ineffective. (B) Anna's friends were surprised by her simple methods.
Output:

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