Atruck is blowing its horn as it approaches a bystander at an intersection. according to the doppler effect, the bystander will notice that the sound- a. increases in pitch b. increases in wavelength c. decreases in frequency d. decreases in speed

good one: produce hormones that plants grow.

bad one: the problem with organic matter is that while plant nutrients are needed for crop growth, they can also stimulate excessive growth of the wrong plants – mainly, algae.

bc blah

explanation:

bc blah