I can't understand this passage, _____ there are no new words in it. [ ]

A. if

B. because

C. though

D. and

用于显示退变髓鞘的染色方法是（）

A.WeigeIt-Pal染色法

B.Marchi染色法

C.Kullshitsky染色法

D.Luxolfastblue染色法

E.Weil染色法