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

Counter example means the opposite. It means we have to show an example that proves the original statement wrong.
so the counter example would be : the sum of 2 consecutive integers equals a prime number. (not a composite number)

So ur counter example would be : 6 + 7 = 13

It is 94.7% that uses the metric system

Welp life just is hard