Which choices below allow for primary succession to take place?

select one or more:
a. burned out forest
b. glacial till
c. lava flow
d. sand dunes

In many humans, exposing the skin to sunlight over prolonged periods of time results in the production of more pigment by the skin cells (tanning). this change in skin color provides evidence that -

What drives the atp synthase reactions that produce atp

How can an organ, such as the lungs, work for multiple body systems?