adverb modifies a verb, adjective, or other adverb to indicate the genuineness or sincerity of an action or quality
adjective a word that describes or gives more information about a noun or pronoun, in this case, 'sincere' describes someone or something genuine and honest
verb Trusting is a present participle form of the verb trust, which means to have confidence in or rely on someone or something.
adjective Trusting can also be used as an adjective to describe someone who has a tendency to trust others easily.