Answer: 0.69 m/ mile.
Explanation:
The altitude gradient between two cities X and Y = 
Given: Two cities are separated by 200 miles.
City X has an altitude of 122 meters.
City Y has an altitude of 260 meters.
The altitude gradient between two cities X and Y =

Hence, the altitude gradient between the two cites = 0.69 m/ mile.
Answer:
D
Explanation:
It is often like this: cell->tissue->organ->system
Answer:
d A wave Carrie's electricity ,a particle carries a magnetic chaege
Objects stop emitting radiation only at 0 K, but objects may not reach 0 K, ever. Thus, no object would ever stop emitting radiation.