Elements can combine to form molecules, like o2 or co2. elements combine to form molecules and these elements are joined together by
a. chemical bonds.
b. nuclear energy.
c. sharing nuclei.
d. attractive forces.

a. Chemical bonds.

Explanation:

Hello,

In this case, it is necessary to know that when two elements are not stable by their own they should bond with an other atom of the same element via chemical bonds whereby the valence electrons act as bridges connecting the atoms. Some examples are diatomic-gaseous hydrogen, oxygen, nitrogen, chlorine, iodine, fluorine and bromine. Moreover, such chemical bonding is represented by lines binding the elements as shown on the attached picture.

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i think the answer is terrae but not 100 percent sure. ▓▬▬ §

the answer is minerals.