A bus is traveling at a constant speed along a straight portion of road. The equation

Choice C is correct. It’s given that $t$ represents the number of seconds after the bus passes the marker. Substituting $2$ for $t$ in the given equation $d=30t$ yields $d=30\left(2\right)$, or $d=60$. Therefore, the bus will be $60$ feet from the marker $2$ seconds after passing it.

Choice A is incorrect. This is the distance, in feet, the bus will be from the marker $1$ second, not $2$ seconds, after passing it.

Choice B is incorrect and may result from conceptual or calculation errors.

Choice D is incorrect. This is the distance, in feet, the bus will be from the marker $3$ seconds, not $2$ seconds, after passing it.