human
Question: Just a few days ago, Beth waded into her family's pond. Now when she stepped off the bank the pond was hard and she could walk on the surface. What happened?

Choices:
A) a cold front had moved into the area
B) The pond had drained into an underground river
C) There was a lot of algae on the pond's surface
D) It had rained the night before
gpt
The correct answer is 0: a cold front had moved into the area.