Mason is a captain of a tourist cruise to the Statue of Liberty. He identified a few relevant functional relationships and modeled them: Function | Input | Output - | - | - $P$| Duration of the cruise, $r$ | Average number of photos taken by each passenger, $P(r)$ $D$ | Speed of the ship, $k$ | Duration of the cruise, $D(k)$ $S$ | Rate of the river current, $x$ | Speed of the ship, $S(x)$ **The expression $D(S(x))$ represents which of the following?** [[☃ radio 1]]