Postgraduate medical-science integration task 65: Which statement best describes competitive antagonism? Focus on pharmacology in this variation.

A. A reversible competitive antagonist shifts an agonist concentration-response curve to the right without reducing maximal response when enough agonist is available B. A reversible competitive antagonist necessarily lowers the maximal response even when much higher agonist concentrations are available C. An irreversible antagonist permanently occupies receptors, so increasing agonist concentration fully restores the original maximal response D. A competitive antagonist increases agonist potency by shifting the concentration-response curve left while leaving receptor occupancy unchanged