题目内容：

17.56
beneath each of the following sentences there are foyr choices marked
A.B.C.D.choose the one answer that is closest in meaning to the sentence
the only problem is that it's impossible to find parking
a.finding parking becomes the biggest problem
b.to finding parking is the only problem impossible to solve
c.it is the number one problem to find parking
d.it is not possible for people to find parking