In the context of the described diagram with two parallel horizontal lines (PS and RQ) and a slanted line (RS) intersecting them, the correct symbol to insert in the statement should indicate the relationship between the two lines.
Given that PS and RQ are parallel lines, the appropriate symbol to illustrate that relationship is the "parallel" symbol, which is represented as \(\parallel\).
Thus, the completed statement would be:
\( PS \parallel RQ \)