Which statement explains why the bonds between nonmetals tend to be covalent? the bonds are found to be nondirectional. they have large differences in electronegativity. they have small differences in electronegativity. they have ions that produce an electrostatic pull.

Correct  They have small differences in electronegativity (statement 3)
Reason: 
The nature of chemical bond between atoms is primarily driven by the electronegativity  difference between constituent atoms. If electronegativity difference between constituent atoms is significantly higher, ionic bond formation is preferred. On other hand, low difference in electronegativity values, favours formation of covalent bond. 

C: plants and animals

Ions gain or lose electrons