1. The problem asks to identify which variable is independent and which is dependent between time spent driving $t$ and distance driven $d$. 2. In general, the independent variable is the one you control or choose, and the dependent variable depends on the independent variable. 3. Since distance $d$ depends on how long Sterling drives (time $t$) and his speed, time $t$ is the independent variable and distance $d$ is the dependent variable. 4. Therefore, the correct description is: The variable $d$ is the dependent variable because it depends on the amount of time spent driving, $t$. 5. This matches option B. 6. Hence, the answer is option B: $d$ is dependent on $t$.