Answer:
b: -30 feet
Explanation:
Process of elimination. the answer must end in 5 or 0, because we are moving at a rate of -5, and any multiple of 5 or -5 ends in 0 or 5. this eliminates a or c. the answer must be negative because we need the TOTAL change in altitude, and we are traveling towards the ground, which eliminates d. (i may be mistaken, and the wording actually means you are travelling "towards" the ground but the negative means you are going in the opposite direction of the ground, in which case the answer is d: 30 feet)