The electromagnetic waves with the most energy have the greatest period
b) wavelength
c)
frequency
d) color

Frequency is the amount of times the particle moves back and forth per second, more or less. The more energy, the higher the frequency. At the same time, the more energy means you'll have a shorter wavelength (aka period). Color only applies to the visible spectrum.

frequency

Explanation: The greater the number of waves appear the greater the energy. The smaller the number of waves appear the lower the energy.

Frequency is the number of times waves appear.

when it gains or loses electrons

answer: the exterior temperature of commercial jet planes as they leave the stratosphere and return to the ground increases steadily.

explanation:

the lower most layer of atmosphere is troposphere which extends from 0 to 12 km above the surface of the earth. the temperature initially decreases as distance is increased from the earth's surface. commercial jets fly in lower part of the stratosphere. the stratosphere extends upto 50 km. the temperature in stratosphere starts rising again due to presence of ozone which traps the uv rays.

thus, when the planes leave the stratosphere and return to the ground, the exterior temperature increases steadily.