question_answer

Which of the options correctly combines the following two given sentences without changing the meaning?

The old books were very difficult. The new books are very simple.

A)  If the old books are very difficult, the new books are very simple.

B)  Whereas the old books were very difficult, the new books are very simple.  

C)  Although the old books were very difficult, the new books are very simple.

D)  When the old books are very difficult, the new books are very simple.