I'll give you a question, please answer with step-by-step reasoning process.
A colorful pebble falls on a goldfish, where is the pebble?\nOptions:\n- aquarium\n- creek\n- pet store\n- playground\n- pond

aquarium
Aquariums have colorful pebbles for show.

aquariums often contain goldfish.

Aquariums are made of glass and are transparent.

One can only watch a pebble fall on a fish in an aquarium.

.

So, the final answer is aquarium