7536. Only those who are gullible take every advertisement seriously.

✅ The correct answer is option C.
fallible : capable of making mistakes or being wrong.

enthusiastic : having or showing intense and eager enjoyment, interest, or approval.

unsuspecting : (of a person or animal) not aware of the presence of danger; feeling no suspicion.

unrealistic : not realistic.

gullible : easily persuaded to believe something; credulous.

Synonym of gullible is unsuspecting