Answer
$\subseteq$
Work Step by Step
$\displaystyle \mathrm{Suppose\ we\ define} \ A\ =\ \ \{1,4,6,8\}$
$\text{To determine which symbol goes in the blank, recall one of the properties of the empty set:}$
$\displaystyle \mathrm{``For\ any\ set\ } A\mathrm{,\ the\ empty\ set\ is\ a\ subset\ of} \ A"$
$\displaystyle \mathrm{This\ can\ be\ written\ symoblically\ as} \ $:
$\displaystyle \emptyset \ \subseteq A$
$\displaystyle \mathrm{Since\ we\ defined} \ A\ \mathrm{to\ represent} \ \{1,4,6,8\} ,\ \mathrm{we\ can\ conclude\ that\ }$
$\displaystyle \emptyset \ \subseteq \{1,4,6,8\}$
