Which of the following is true of clouds at medium altitudes?

a. they are a sign of severe weather.
b. they generally produce lightning.
c. they are made of ice crystals.
d. they cause light rain and snow.

The one that is true of clouds at medium altitudes is : 
B. they generally produce lightning
It happens because of the movement of the electrons in the cloud that triggers a spark of electricity

Master planned communities outside of chicago. note: population density means people living in an area per square mile. chicago, an urban and highly populated area has a much more higher density than a desert, amish community, settlement, or nomadic region.

The answer is    d.  central highlands