what their friendships are based upon the important thing to remember is both of them are

问题补充：

what their friendships are based upon, the important thing to remember is both of them are friendships.

A. Regardless that

B. Regardless of, that

C. Though, /

D. Despite, what

答案：

A. Regardless that

(答案→)B. Regardless of, that

C. Though, /

D. Despite, what

解析：考查固定词组和表语从句。Regardless of/despite不管；尽管；后面接名词或者名词短语；though后面接句子表示尽管；第二空that引导表语从句，that在句中不充当任何成分，只起引导作用。句意：不管他们的友谊是建立在什么之上的，需要记住的就是他们是朋友。