Consider the question. Of the following two sentences, which one is against common sense?
Options:
- Sentence A: "The babies birthday is the day their parents met."
- Sentence B: "When a baby is born, that day is called its' birthday."

 What is the step-by-step reasoning process to arrive at the answer: Sentence A?
A birthday refers to the day you were conceived as a way to refer to your age so it cannot be the day your parents met.