The President of a Consulting Firm Wants to Minimize the Total

Multiple Choice

The president of a consulting firm wants to minimize the total number of hours it will take to complete four projects for a new client. Accordingly, she has estimated the time it should take for each of her top consultants-Charlie, Betty, Johnny, and Rick-to complete any of the four projects, as follows:
Assume there must be one-to-one matching between consultants and projects. In how many different ways can she assign these consultants to these projects?

A) 4
B) 8
C) 16
D) 24
E) 256