sat-dog

Choice B is correct. It′s given that the airplane descends at a constant rate of $400 \text{feet} \text{per} \text{minute}$. Since the altitude decreases by a constant amount during each fixed time period, the relationship between the airplane′s altitude and time is linear. Since the airplane descends from an altitude of $\mathrm{9,500} \text{feet}$ to $\mathrm{5,000} \text{feet}$, the airplane′s altitude is decreasing with time. Thus, the relationship is best modeled by a decreasing linear function.

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

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

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