Why are viruses considered to be nonliving?

a. they have no genetic material.
b. they cannot use energy.
c. they cannot live outside a host.
d. they do not respond to their environment.

C. they cannot live outside a host

Explanation:

Hope this helsp :))

the dark variety, as they are not visible on the dark tree barks

explanation:

"do a testcross with a homozygous recessive plant."