—Nero is crying. Do you know _______ she's so upset?
—Well, she lost her pet cat which was just like her family member.
A:who
B:what
C:why
D:when
小明在一只装有红色和白色球各一只的口袋中摸出一只球,然后放回搅匀再摸出一只球,反复多次实验后,发现某种“状况”出现的机会约为50%,则这种状况可能是( )