A. is out
B . While B is true it was general that they made important advances, it wasnt something new
We are left with C and D.
D is out... its not really an achievement that contributed to the Golden Age.
You see,the Golden age had to do with other nations and the spread of culture and religion of Islam as well as trade.
SO the answer is C. Islam spread through Western Europe which led to the blending of cultures and helped promote trade.
Hope this helped!