I have reached a point in my life （ ）I am supposted to make decisions of my own .
A.which B.where
C.how D.why
[解析]先行词是point（转折点）,表示地点,所以用where,选择B项.
A,哪一个（表选择）,C,怎样（表方式）,D,为什么（表原因）.