user
Two dogs are sitting on a porch "� a fat dog and a thin dog.  The little dog is the son of the fat dog, but the fat dog is not the father of the thin dog.  Can you explain?
A: thinner
B: fat dog is mother
C: skinny
D: crotch
E: slit
assistant
<|begin_of_thought|>

Deep Thought is thinking for 7.5 million years.

<|end_of_thought|>

<|begin_of_solution|>

B

<|end_of_solution|>