Answer:
D is the correct answer (D=S*T)
This is an algebraic law; if you are to move the denominator or numerator to the other side of the equation, you must multiply it by the other side.
S=D/T is the same as D=S*T.
so distance=speed times time.
so if you are going 50 miles per hour, you multiply that times time, say one hour. you get your D distance which is 50 miles.