Answer:
a. synergism
Explanation:
When two different drugs inhibit a single biochemical pathway of microbes less quantity of each drug is required in combination to produce the effect than when used separately. This effect is called synergistic interaction of drugs.
Both beta-lactam antibiotics such as penicillin and cephalosporin and clavulanic acid serve as beta-lactamase inhibitors and inhibit the beta-lactamase-producing bacteria. Therefore, beta-lactam antibiotics and clavulanic acid are used in combination to control these enteric bacteria.