Let An=(1n,n+1n]A_n = \left( \frac{1}{n}, \frac{n+1}{n} \right]An=(n1,nn+1] for n∈Nn \in \mathbb{N}n∈N (natural numbers, starting from 1). Determine the set S=⋃n=1∞(⋂k=n∞Ak)S = \bigcup_{n=1}^{\infty} \left( \bigcap_{k=n}^{\infty} A_k \right)S=⋃n=1∞(⋂k=n∞Ak).
(0,1](0, 1](0,1]
[1,2][1, 2][1,2]
(0,2](0, 2](0,2]
∅\emptyset∅