Answer:

\(\displaystyle{\left\lbrace{p},{t}\right\rbrace}\subset{\left\lbrace{p},{r},{s},{t}\right\rbrace}\Rightarrow{F}\subset{D}\)

This is because:\(\displaystyle{F}={\left\lbrace{p},{t}\right\rbrace}{\quad\text{and}\quad}{D}{\left\lbrace{p},{r},{s},{t}\right\rbrace}\) as all elements in set F exist in that of set D, F is a subset of D

\(\displaystyle\therefore{T}{r}{u}{e} \)