If the Temperature Is Constant, Then the Atmospheric Pressure P

Multiple Choice

If the temperature is constant, then the atmospheric pressure P (in pounds/square inch) varies with the altitude above sea level h in accordance with the law where p​₀ is the atmospheric pressure at sea level and k is a constant. ​
If the atmospheric pressure is 17 lb/in.² at sea level and 11.5 lb/in.² at 5,000 ft, how fast is the atmospheric pressure changing with respect to altitude at an altitude of 15,000 ft? Give the answer to four decimal places.

A) 0.0004 lb/in.²/ft
B) 0.0006 lb/in.²/ft
C) 0.0003 lb/in.²/ft
D) 0.0007 lb/in.²/ft
E) 0.0005 lb/in.²/ft