How many positive prime numbers are less than the integer n?

Lets consider all the positive prime numbers less than 20:

2, 3, 5, 7, 11, 13, 17, 19

(1) 14<n<20 and n is an integer

Value of n |||||||| positive prime numbers less than n
15 |||||||| 6 (2, 3, 5, 7, 11, 13)
16
17
18 |||||||| 7 (2, 3, 5, 7, 11, 13, 17)
19

Since we get 2 different answers, (1) is not sufficient

(2) 13 < n < 17


Value of n |||||||| positive prime numbers less than n
14 |||||||| 6 (2, 3, 5, 7, 11, 13)
15 |||||||| 6 (2, 3, 5, 7, 11, 13)
16 |||||||| 6 (2, 3, 5, 7, 11, 13)

Since (2) gives a definitive answer that there are 6 positive prime numbers less than n (whether n = 14, 15, or 16), (2) is sufficient.

The answer is B.