Consider the question. Test for natural language inference.
Premise: "As a man walks down the street a pigeon swoops behind him."
Hypothesis: "The man is aware of the pigeon."
Is the hypothesis entailed by the premise?
Options:
- yes
- no
- it is not possible to tell
 What is the step-by-step reasoning process to arrive at the answer: it is not possible to tell?
A man may or may not be aware of a pigeon swooping behind him.