The value of integral ∫^[infinity]₀ [n⋅e⁻ˣ]dx is equal to (where [⋅] denotes the greatest integer function and n∈N,n>1)
a. In(nⁿ⁻¹/n¹)
b. In(nⁿ/n¹)
c. In(nⁿ⁺¹/n¹)
d. 0