The Following Table Shows the Relationship Between the Speed of a Computer's

The following table shows the relationship between the speed of a computer's CPU and its benefits and costs.Assume that all other features of the computer are the same (that is, CPU speed is the only source of variation) , and only the CPU speeds listed below are available for purchase. Choosing a 3.5GHz computer would be irrational because:

A) its marginal benefit is less than its marginal cost.
B) its marginal benefit is equal to its marginal cost.
C) it is impossible to tell the difference compared to a 3.0GHz computer.
D) its marginal benefit is greater than its marginal cost.