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 seamlessly connects with the rest of the story, indicating your choice as 'a' or 'b'. If both sentences are plausible, pick the one that makes more sense.
Q: Title: Science Experiment. Sentence 1: My child asked me if we could do a science experiment at home. Sentence 2: I looked online for one that seemed fun. Sentence 3: We mixed cornstarch and water to make a non-Newtonian fluid. Sentence 4: My child was very curious about how such a thing could be happening. Choices: a. I was out of my depth and could not explain it to my child. b. Bob had the contractor install the new fence.
A:
a