Questions Refer to the Passage Below

Questions refer to the passage below.
"The Eastern Question, which is primarily involved in any discussion regarding the future of the Turks, may be called the ghost that stalks . . . the hall at Paris in which the representatives of the great nations are at present assembled for deliberation as a crisis in the world's history . . .
[At] the close of the eighteenth century the definite decline of Turkey brought the Eastern Question to an acute stage, the European Powers alternately supported the "Sick Man of Europe" or . . . hasten[ed] his demise. [Take the] famous remark of Lord Salisbury after the Crimean War, in which he apologized . . . for England's taking what turned out to be the wrong side, by declaring that she had unfortunately backed the wrong horse, is characteristic of the policy that was pursued in regard to Turkey by all the Powers. It was a question not of the right side, but of the winning side."
The Decline of the Ottoman Empire (1919) Morris Jastrow, Jr., scholar
-Which of the following was a key factor in the weakening of the Ottoman Empire through the latter half of the nineteenth century?

A) Continued conflict with Spain for control of the Mediterranean Sea
B) Failure to modernize industry and the economy, and to reform government
C) Failure to defeat Russia during the Crimean War, opening the door for Russian expansion around the Black Sea
D) Failure to capture the city of Vienna from the Hapsburg Empire.