A. 中国有上百的岛屿,在所有岛屿之中,台湾是最大的,所以是in which (which指代前面的islands)
Taiwan is the largest island of China
D...恢复语序,是。。。The largest island of the hundreds of islands is Taiwan...
选D,the largest of the hundreds islands is Taiwan.这样理解就OK了
d