GWD数学题一道求解啊

Q26:

K is a set of integers such that if the integer r is in K, then r + 1 is also in K.  Is 100 in K?

(1)     50 is in K.

(2)     150 is in K.

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.

why is a?

這題我是這樣想的~~因為他給的是r+1~r=50  r+1=51.........

所以你只有辦法用低於100的數字去證明100在這個SET裡面!!

R=150的話~R+1=151.....已經超過100~故沒辦法證明