Answer :
The correct answer is Crimean war.
Crimean war weakened the economy of Ottoman empire.
Crimean war was a conflict for militaries where russia empire lost their alliance of Sardinia, Britain, France and Ottoman empire.
The cause of the conflict was christian minorities rights to Holy land and among the Ottoman Empire.
Russia promoted rights of eastern orthodox church while French promoted rights of Roman catholic.
The conflict which was long was a cause which involved Ottoman empire decline and France and Britain unwilling to allow Russia to gain power and territory at expense of Ottoman.