Definition: 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 does not connect with the rest of the story, indicating your choice as 'a' or 'b'. If both sentences are plausible, pick the one that makes less sense.
Input: Title: Never returned. Sentence 1: Alex's son begged him to go hiking with a group of Alex's friends. Sentence 2: Alex was concerned as his son was only 3. Sentence 3: But Alex's friends promised to look after him. Sentence 4: On the trail, the friends got too caught up in their conversation. Choices: a. Alex's son vanished and no one knew how. b. Synthia was able to live happily after that despite her injury.
Output:
b