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.

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