Which of the following statements regarding the expansion of (x+y)^n is correct? A. For any term x^ay^b in the expansion, a+b=n
B. The coefficients of x^ay^b and x^by^a are equal
C. The coefficients of x^n-1 and y^n-1 both equal one
D. For any term x^ay^b in the expansion, a-b=n