Solution:
If we choose a usual coordinate axis, an object going down would be traveling a negative distance, so a possible answer would be:
C. skiing 161 ft down a mountain.
On the other hand, An expense of money involves a waste of money, which is negative. So another possible answer would be:
D. spending $spending $161 on vacation.
Then, we can conclude that the correct answer would be:
C. skiing 161 ft down a mountain.
D. spending $spending $161 on vacation.