Verified answer

Answer:

-1

Step-by-step explanation:

here -1 is only possible

So when $a = 3$ we have $a,a + 2,a + 4$ are all prime numbers. There is no other prime number $a$ for which $a + 2,a + 4$ are also prime numbers. So the number of positive solutions for $a$ is 1. Hence, the correct answer is (C) one.

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