(Shamir secret sharing): in some security system, to share a secret S, they use Shamir's secret sharing. the users in the system are divided to 3 levels of authorization: A, B, and C. To recover S, we need:

A) two users from A

OR

B) one user from A in addition to three users from B and 5 users from C.

1)describe and elaborate how a secret can be shared in this cryptosystem

2)assuming that in level A there are only 2 users, and one of themdecided to resign. his part of the secret, X, he shares with all of the participants, except the other user from level A, so to recover X we need 4 participants from B and one participant from C. describe the new secret sharing cryptosystem. what does each participants hold and how to recover S?

please give a full answer and explain so i can learn for your answer to the exam. the answer should be in academic level and it is a question i did not know how to solve as preparation to an exam, so i need full answer i can learn from. thank you very much