Carcass wrote:
That Alexander Solzhenitsyn languished for many years in a Siberian prison camp can perhaps account for ______ the tone of many of his novels.
A. bleak
B. sentimental
C. cogent
D. sanguine
E. persistent
F. grim
Alexander Solzhenitsyn's many novels had a certain tone. He spent many years in Siberian prison languishing, therefore the tone must be related to languish.
Bleak & grim are good fits for the blank. Hence option A and F are correct answers.