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Consider the series $\sum_{n=1}^{\infty }\frac{1}{n\left ( n+1 \right )}$. Find the first four partial sums for this series.

$\cfrac{1}{2},\cfrac{1}{5},\cfrac{1}{10},\cfrac{1}{17}$

$\cfrac{1}{2}, \cfrac{7}{10}, \cfrac{4}{5}, \cfrac{73}{85}$

$\cfrac{1}{2},\cfrac{1}{6}, \cfrac{1}{12}, \cfrac{1}{20}$

$\cfrac{1}{2}, \cfrac{2}{3}, \cfrac{3}{4}, \cfrac{4}{5}$