Why Did European Scholars Owe So Much to the House

Why did European scholars owe so much to the House of Wisdom in Baghdad?

A) Its scholars continued experiments first conducted by Galen and others.
B) Scholars from there sent copies of original works to European scholars.
C) Its scholars translated ancient Greek works into Arabic, which were later translated into Latin.
D) The founder of the House maintained an open door to European scholars.
E) Its scholars devised the best ink and materials to preserve ancient texts.