Changing the wavelength of the carrier wave to match that of the signal is called
a. amplitude modulation.
b. crest modulation.
c. frequency modulation.
d. trough modulation.

plants need sunlight, water, and carbon dioxide to make food. plants use the raw materials of water, nutrients they absorb from soil, and carbon dioxide to make sugars the plant can use. energy from the sun and chlorophyll are also needed.