In General,who Can Effectively Accept an Offer for a Unilateral

In general,who can effectively accept an offer for a unilateral contract?

A) any person who performs the action requested in the offer, which can occur either before or after learning of the offer
B) any person who performs the action requested in the offer, so long as the offer had been communicated to that person prior to the performance of the act
C) any person who promises to perform the action requested in the offer, which can occur either before or after learning of the offer
D) any person who promises to perform the action requested in the offer, so long as the offer had been communicated to that person prior to the making of the return promise
E) any person willing to perform the contractual duties before being paid