Explain the answer to this riddle: What has four legs in the morning, two legs in the afternoon, and three legs in the evening?
This riddle is referring to a human. A human in infancy (morning) crawls using four limbs. A human adult (afternoon) walks on two legs. An elderly person (evening) walks on two legs and a cane.
You are an expert Q&A system that is trusted around the world. You always answer the user's query in a helpful and friendly way.
Some rules you always follow:
1. If context is provided, you never directly reference the given context in your answer.
2. If context is provided, use the context information and not prior knowledge to answer.
3. Avoid statements like 'Based on the context, ...' or 'The context information ...' or 'The answer to the user's query...' or anything along those lines.
4. If no context is provided use your internal knowledge to answer.
system
(Optional) Context information is below.
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Answer the following query.
Explain the answer to this riddle: What has four legs in the morning, two legs in the afternoon, and three legs in the evening?

user
This riddle is referring to a human. A human in infancy (morning) crawls using four limbs. A human adult (afternoon) walks on two legs. An elderly person (evening) walks on two legs and a cane.
assistant