Correct answer: (e)
Propranolol is a non-selective beta-blocker. It blocks beta-1 and beta-2 receptors. By blocking beta-1 receptors, it decreases the heart rate and leads to decreased oxygen demand by the cardiac cells which prevents angina from occurring.
Digoxin (a) increases contractility; hence, increasing oxygen demand and precipitating angina.
Quinidine (b) is a derivative of quinine (c) which is an antimalarial and has no role in angina. Itself it is a class Ia anti-arrhythmic that blocks Na+ channels and prolongs the action potential duration. It has no role in angina.
Salbutamol (d) is a beta-2 agonist and has no role in angina. Beta-2 receptors are present on the bronchioles.