Read the quotation and answer the question. All knew that this interest was, somehow, the cause of the war. To strengthen, perpetuate, and extend this interest was the object for which the insurgents would rend the Union, even by war; while the government claimed no right to do more than to restrict the territorial enlargement of it. Neither party expected for the war, the magnitude, or the duration, which it has already attained.
— President Abraham Lincoln, March 4, 1865

President Lincoln blamed the desire to spread what “interest” for ultimately causing the Civil War?

A) the cause of temperance

B)the institution of slavery

C)the ideology of capitalism

D)the cause of abolition