If the Subject Matter of an Offer Becomes Illegal,what Is

If the subject matter of an offer becomes illegal,what is the result?

A) The offer immediately terminates.
B) The offer is still valid,as long as the offer was made at least three calendar days before the subject matter of the offer became illegal.
C) The offer is still valid,as long as the offer was made at least seven calendar days before the subject matter of the offer became illegal.
D) The offer is still valid,as long as the offer was made at least thirty calendar days before the subject matter of the offer became illegal.
E) The offer is still valid,as long as the offer is part of an otherwise enforceable option contract.