Authority is power that people view as legitimately exercised over them, while coercion is power they consider unjust.
a. true
b. false

Yes, this is correct.

Authority is usually a good thing, for example the elected President of the Unites States has the authority people people gave him the authority.
On the other hand, coercion is seen rather as a negative concept and a problem (and can be corrected to bullying)