Premise: "Skateboarder grinds a concrete railing."\nBased on this premise, can we conclude that the hypothesis "Someone is skateboarding." is true?\nOptions:\n- yes\n- it is not possible to tell\n- no
Think hard. Detailed solution:
yes
A skateboarder is someone and if he/she grinds that means he/she is skateboarding.

.

So, the final answer is yes