1959 AMC 12 Question 37 - thichhoctoan.com

Question 37

When simplified the product $$
\begin{aligned} &\left(1-\dfrac13\right)\left(1-\dfrac14\right)\\ &\quad{}\cdot\left(1-\dfrac15\right)\cdots\left(1-\dfrac1n\right) \end{aligned}
$$ becomes:

$\dfrac1n$
$\dfrac2n$
$\dfrac{2(n-1)}n$
$\dfrac{2}{n(n+1)}$
$\dfrac{3}{n(n+1)}$