Final answer:
Theophylline could increase the adverse effects of chocolate toxicity due to its similar pharmacological actions to theobromine, which is found in chocolate.
Step-by-step explanation:
The drug that could add to the adverse effects of chocolate toxicity is B. Theophylline. Chocolate contains theobromine, which is similar in structure and function to theophylline. Both theobromine and theophylline are methylxanthines, and their pharmacological actions include stimulating the central nervous system, diuresis, stimulating cardiac muscle, and relaxing smooth muscle.
Since they share similar mechanisms of action, taking theophylline could exacerbate the effects of chocolate toxicity, leading to increased adverse effects such as nervousness, tremors, or tachycardia.