Why Were the British So Concerned About the Alliance Between

Why were the British so concerned about the alliance between Mahmud II and the Russians, the Treaty of Unkiar Skelessi?

A) Because it would likely increase Russian influence in Istanbul.
B) Because the Russians would join with Mahmud II to defeat Muhammad Ali, a British ally, in battle
C) Because the Russians would help Mahmud II stymie further nationalist movements in the Balkans
D) None of these answers is correct.