Let Bn={q∈Q:0<∣q∣<1n}B_n = \{ q \in \mathbb{Q} : 0 < |q| < \frac{1}{n} \}Bn={q∈Q:0<∣q∣<n1} for each n∈Nn \in \mathbb{N}n∈N (starting from 1). What is the intersection S=⋂n=1∞BnS = \bigcap_{n=1}^{\infty} B_nS=⋂n=1∞Bn?
{0}\{0\}{0}
∅\emptyset∅
Q\mathbb{Q}Q
{q∈Q:q=0}\{ q \in \mathbb{Q} : q = 0 \}{q∈Q:q=0}