Asubstance that enters earth's cycles and does harm to living things is
a. hydrogen.
b. a pollutant.
c. freshwater.
d. oxygen.

Pollutants are substances that do harm to an environment and the beings that live in it. Fresh water and oxygen are beneficial and necessary for life. Hydrogen is a naturally occuring element and isn't harmful. The EPA is a government department that works to prevent pollution.

Since a female is both xx chromosome and the male passes down the x chromosome, than the offspring would be female since a female is xx.