A predicate adjective is the first adjective found after a linking verb such as to be, or to look, or to smell, etc. So, in this case, the only sentence where there is an adjective following a linking verb (looks) is B. Jerry looks ill today. Here, the predicate adjective is the word ill. There are no adjectives in the remaining sentences: at the map and into the microscope are prepositional phrases, and disdainfully is an adverb.
