This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pharmacodynamics, Subject name: Pharmacology
Which of the following drug combination is supraadditive 
Select and explain. 
A. Nitrous oxide + halothane as general anaesthetic, B. Glibenclamide + metformin as hypoglycaemic, C. Sulfamethoxazole + trimethoprim, D. Ephedrine + theophylline as bronchodilator
C: Sulfamethoxazole + trimethoprim
Answer: C: Sulfamethoxazole + trimethoprim 
Explanation: Additive: Effect of drug A + B = effect of drug A + effect of drug B Aspirin + paracetamol as analgesic/ antipyretic Nitrous oxide + halothane as general anaesthetic Amlodipine + atenolol as antihypeensive Glibenclamide + metformin as hypoglycaemic Ephedrine + theophylline as bronchodilator Supra additive : Effect of drug A + B > effect of drug A + effect of drug B Acetylcholine + Physostigmine Inhibition of break down Levodopa + carbidopa/ Inhibition of peripheral metabolism benserazide Adrenaline + cocaine/ desipramine Inhibition of neuronal uptake Sulfamethoxazole + trimethoprim Sequential blockade Antihypeensives enalapril+ hydrochlorothiazide: Tackling two contributoryfactors