Grove is seeking to avoid performing a promise to pay Brook $1,500. Grove is relying on lack of consideration on Brook’s part. Grove will prevail if he can establish that

a. Prior to Grove’s promise, Brook had already performed the requested act.

b. Brooks’ only claim of consideration was the relinquishment of a legal right.

c. Brook’s asserted consideration is only worth $400.

d. The consideration to be performed by Brook will be performed by a third party.