42.
(A)whom
(B)what
(C)which
(D)where

This is also an affordable way of international learning through    which 

A) Whom 只能代"人"這裡是 an affordable way "這個負擔的起的方式"算是物
B )through what 透過"甚麼"  -->明顯不對

C)through    which  代替an affordable way(物)。而且which的前面常常加介係詞e.g. in which

D)where 地方 通常不會加介係詞 ((但是這個我不確定，網友大大如果知道可以跟我說一下，我只是憑習慣選C

This is also an affordable way of international learning through  (C)which students can establish a friendship with people of similar age and learn together without having to spend much money going abroad in order to do so. As the word, collaborative, indicates, this is a pedagogy that focuses on a student-centered approach of learning with teachers playing merely the role of    43.

(A)whom 
(B)what 
(C)which 
(D)where .