Answer:
its either all animals or only mammals. the thing with all animals is that they do have life cycles but not the same as like say humans or elephants, some are complicated.
Would it be lack of water and food?
Answer:
The answer to your question is below
Explanation:
Covalent bonds are bonds between to atoms that share a pair of electrons, there are three kinds of covalent bonds but I'll describe only two:
Covalent non polar bond: is a covalent bond between two elements of the same element. Ex two hydrogens, two chlorine, two oxygenes, etc.
Covalent polar bond: is a covalent bond between 2 elements of different elements, for example: hydrogen and chlorine or nitrogen, they are polar because on of the element that form it is smaller than the other one, then a partial positive and a partial negative charge is formed.