Which option describes cations?

D

Explanation:

A cation is a positively charge ion, such as a sodium ion, as when it becomes an ion, it gives away electrons, becoming positively charged.

The opposite is an anion, which is a negatively charged ion, such as oxygen as it receives elections from the cation when forming an ionic bond.

i believe the answer is c

any abiotic or biotic factor in an ecosystem that causes a population's size to slow or decrease is a limiting factor.