GWD23-16

Q16:

If k is a
positive integer, what is the remainder when 2^k is divided by
10 ?

(1)
              k is divisible by 10.

(2)
              k is divisible by 4.

A. Statement (1) ALONE
is sufficient, but statement (2) alone is not sufficient.

B. Statement (2) ALONE
is sufficient, but statement (1) alone is not sufficient.

C. BOTH statements
TOGETHER are sufficient, but NEITHER statement ALONE is
sufficient.

D. EACH
statement ALONE is sufficient.

E. Statements (1)
and (2) TOGETHER are NOT sufficient.

Answer:   

2^4=16,

16的任意次方，结果的个位都是6，被10除，余数都是6

why the first condition is not sufficient??