All of this proves that we must have a profound study of properties of metals. 句中的profound在汉译时，转换为哪种词性？

All of this proves that we must have a profound study of properties of metals. 句中的profound在汉译时，转换为哪种词性？
A.名词
B.动词
C.形容词
D.副词
正确答案：副词