16) How many of the following statements about natural numbers are true?

(i) Given any two consecutive odd numbers, at least one is prime.

(ii) Given any three consecutive odd numbers, at least two are prime.

(iii) Given any four consecutive odd numbers, at least one is not prime.

(iv) Given any five consecutive odd numbers, at least two are not prime.
(A) None
(B) one
(C) two
(D) three
(E) four.
16) The answer is (B). (i) is false, for example, 25 and 27 are two consecutive odd numbers, both of which are not prime. (ii) is false, for example, 23, 25, and 27 are three consecutive odd numbers, two of which are not prime. (iii) is true because given four consecutive odd numbers (in fact, three would suffice), at least one is divisible by 3 and therefore not prime (the case $1,3,5,7$ has 1 which is not prime). (iv) is false, for example, $11,13,15,17,19$ are five consecutive odd numbers, of which only one is not prime.