Define the word atom.

a particle of matter that uniquely defines achemical element

Explanation:

atoms make up everything you can see and even stuff you can't see

Basic unit of a chemical element.

Explanation:

If defined as the smallest unit of matter, this is incorrect, as that would be electrom, protn, nuetron, that stuff, and even smaller is quarks that make up the prior three things. So DONT define as smallest unit.

which

if you listed your answers right then i believe your answer is b.