Which of the following must be true to consider something to be alive?
a. it must be able to replicate its dna
b. it must be able to respond to light
c. it must be able to convert energy from one form to another
d. it must be able to move

A. it must be able to replicate its dna

Explanation:

To consider something to be alive the organism must have a DNA a form of genetic material which is replicated by the cellular machinery. This genetic material is necessary for proper growth and development of cells.

Viruses are not considered as living as they use the host cell machinery to replicate their DNA.

for the points

for  example, forests have higher evapotranspiration than other ecosystems,  such  as grasslands, because of their deeper roots and greater leaf area. thus forests have a net moistening effect on the atmosphere and become a moisture source for downwind ecosystems.