The smallest value of n, for which 2n+1 is not a prime number, is	Choose the correct choice from the following.
A) 3 B) 4 C) 5 D) none E) 6

Rationale: "solution ( 2 × 1 + 1 ) = 3 . ( 2 × 2 + 1 ) = 5 . ( 2 × 3 + 1 ) = 7 . ( 2 × 4 + 1 ) = 9 . which is not prime , n = 4 . answer b"
Answer: B