Read the following premise and answer if the hypothesis is true.
A man is grinding his skateboard on a guard rail.
Hypothesis: The man is a professional skateboarder.. Is the answer "Yes", "No", or "It's impossible to say"? Respond with only the answer and no additional text.
It's impossible to say
It's impossible to say. Grinding on a guard rail can be a common trick for both professional and beginner skateboarders.