The answer is option D: He had everything but the panting and the drool; he also seemed overly happy, perhaps from too much caffeine.
The excerpt from "A Baker's Dozen," by David Matherne, indicates that the person has no panting or drool, but has had a lot of caffeine and has a feeling of happiness. Option A mentions the same things in a simple sentence, but alternative D is expressed in a more improved way - with two independent clauses separated by a semicolon.
Option B is incorrect because it claims that the person has everything, and option C states that he or she has drooling, which is not true.