Assertion:
If a cat crosses one's path, it is a bad omen.
RI. It is believed that cat brings bad luck.
RII. Many people had accidents after a cat crossed their path.
Answer: B
RI is not valid, as it talks about the cat itself and the assertion is about a cat crossing someone's path. RII can be a valid reason. As the assertion in more of a superstition, which in all probability is based on some collection of bad events in the same regard, hence only II is the reason.