Choice "D" is correct. To be effective, consideration must be legally sufficient, which means something that the law recognizes as consideration.
Choice "b" is incorrect. The courts do not require contracts to be "fair," giving each party equal benefit.
Choice "a" is incorrect. There is no requirement that consideration be exchanged simultaneously. For example, in a unilateral contract, the promise is given first and the performance, which is the consideration on the other side, comes later.
Choice "c" is incorrect. The courts will not inquire into the fairness of a bargain.
