Chemical bonds
a. are always ionic.
b. combine compounds to form elements.
c. are always covalent.
d. hold atoms together to form compounds.

. a pyramid of numbers differs from an ecological pyramid because it
a. shows the amount of energy within each trophic level.
b. displays the number of organisms at each trophic level.
c. is organized by trophic levels, while an ecological pyramid isn't.
d. attempts to describe a food chain or food web.