He is worth().A. B.trusting

The correct answer is B. trusting. The phrase "be worth doing" requires a gerund (verb form ending in -ing) to follow. "Worth" functions as an adjective here, and the structure "be worth + gerund" means something merits the effort or value of that action. For example, "This book is worth reading" or "The movie is worth watching." In this sentence, "He is worth trusting" means he merits being trusted.

Other options would either be grammatically incorrect (like a bare infinitive "trust") or semantically inappropriate. The gerund form "trusting" is the only grammatically valid choice to complete the sentence correctly.