If any of you want to join the california LSAT studying discord you should! It just got started a few days ago in the forum but feel free to join! it's https://discord.gg/AVKcyKmc or you can go check the forum out : )

You are absolutely on the right track with your thinking. In this case, ALL cats are mammals, yet the relationship is still one of sufficiency not necessity because there are also mammals that are NOT cats. Membership in subset A is sufficient to determine that X is a member of the superset B, but it is not required as there may be other sets belonging to the superset B.