[JEE Main 2013] source incomplete set s not defined in extraction min z in s 1 3i

[Source incomplete — set $S$ not defined in extraction] $\min_{z\in S}|1-3i-z|=$

(a) $\frac{2-\sqrt3}2$
(b) $\frac{2+\sqrt3}2$
(c) $\frac{3-\sqrt3}2$
(d) $\frac{3+\sqrt3}2$