Consider the sequence $$y_n = \frac{1}{\int_{1}^{n}\frac{1}{(1 + x/n)^3}dx}$$
for $n = 2, 3, 4, ...$. Which of the following is TRUE?
(A) The sequence $\{y_n\}$ does not have a limit as $n\rightarrow \infty$.
(B) $y_n\leq 1$ for all $n = 2, 3, 4, ...$
(C) $\lim_{n\rightarrow\infty} y_n$ exists and is equal to $6/\pi^2$.
(D)$\lim_{n\rightarrow\infty} y_n$ exists and is equal to $0$.
(E) The sequence $\{y_n\}$ first increases and then decreases as $n$ takes values $2, 3, 4, ...$
