Identify the two series that are the same.
a. Sigma (lower n = 4; upper infinity) n(3/4)^n
b. Sigma (lower n = 0; upper infinity) (n+1)(3/4)^n
c. Sigma (lower n = 1; upper infinity) n(3/4)^(n-1)
a. Sigma (lower n = 4; upper infinity) n(3/4)^n
b. Sigma (lower n = 0; upper infinity) (n+1)(3/4)^n
c. Sigma (lower n = 1; upper infinity) n(3/4)^(n-1)