Which is a counterexample to this conjecture?


The sum of any two consecutive integers is a composite number.


A.

16 + 17 = 33


B.

10 + 11 = 21


C.

6 + 7 = 13


D.

7 + 8 = 15

Verified Answer :

The answer is C.

33,21,and 15 are all composite numbers. Meaning that they had factors other than 1 and themselves. 13 is a prime number because 13 only factors are 1 and itself.

C. 6 + 7 = 13
because 6 and 7 are consecutive integers, but 13 is not a composite number.