A witness in a trial testified that he searched 21 cars, of which 12 were convertibles, 16 had out-of-state plates, and 4 were convertibles with out-of-state plates. Explain why the witness was not telling the truth. 

a. The actual number of convertibles would have to be 8, which does not agree with the witness' testimony that 12 cars were convertibles. 

b. The actual number of convertibles with out-of-state plates would have to be 12, which does not agree with the witness' testimony that convertibles had out-of-state plates. 

c.  The actual number of cars he searched was 28, which does not agree with the witness' testimony that he searched 21 cars. 

d. The actual number of cars he searched was 24, which does not agree with the witness' testimony that he searched 21 cars.