What was the question for this implicit rationale, and corresponding answer?
Two boys laughing while looking at a computer does not imply that one boy made the other laugh or that he did so by showing him a funny video.
 The answer: it is not possible to tell
The question: Can we conclude from "A younger boy wearing headphones with a microphone laughs with an older boy wearing a green t-shirt while looking at a computer screen." that "The boy at the computer made  the younger boy laugh by showing him a funny video."?
Options:
- yes
- no
- it is not possible to tell