What is a chemical reaction? a. a process of bonding substances together
B. a process that leads to have filled valence shells
following the octet rule
C. a process that releases or consumes energy
D. all of the choices

A chemical reaction is defined as per encyclopedia Britannia as a "a process in which one or more substances, are converted to one or more different substances, the products."

So A is correct, B is correct, C is correct.

So that means we choose D as they're all correct.

you need to have a picture of the atom that way we can answer it

it's c (engineer's do their work with mechanical stuff not on any living being)