17. During the nineteenth century Emily Eden and Fanny Parks journeyed throughout India, sketching and keeping journals forming the basis of news reports about the princely states where they had visited.

(A) forming the basis of news reports about the princely states where they had

(B) that were forming the basis of news reports about the princely states

(C) to form the basis of news reports about the princely states which they have

(D) which had formed the basis of news reports about the princely states where they had（E）

(E) that formed the basis of news reports about the princely states they

E 中, STATES 后的定语从句 THAT 可以省略吗? 如果可以, 何时省略?

请指教.