Although some parents believe that the local all-girls school should begin to admit boys, others claim that girls would participate actively in class only if they had all-girls classes.

A)that girls would participate actively in class only if they had all-girls classes
B)that girls will only participate actively in a class if it is all-girls
C)that girls will only participate actively in an all-girls class
D)that girls would participate actively only in a class that were all-girls
E)that girls in all girls-classes will participate actively in that situation only

[spoiler]OA:C[/spoiler]