Question

insert ⊆ or ⊈ so that the resulting statement is true. ∅____{p, q, r, s, t} choose the correct answer below. ⊈ ⊆

Explanation:

Step1: Recall subset definition

The empty - set $\varnothing$ is a subset of every set. A set $A$ is a subset of a set $B$ (denoted $A\subseteq B$) if every element of $A$ is also an element of $B$. Since the empty - set has no elements, the condition is vacuously true for any set $B$.

Answer:

B. $\subseteq$