We are given a set $X = \left \{x_1, x_2, \ldots , x_n \right \}$ where $x_i = 2i$. A sample $S$ (which is a subset of $X$) is drawn by selecting each $x_i$ independently with probability $P_i = \frac 12$. The expected value of the smallest number in sample $S$ is:
a) $1/n$
b) $2$
c) $\sqrt n$
d) $n$