The term for interactions where the combined effect is greater than the sum of individual effects is:

• A. Additivism
• B. Antagonism
• C. Sensitivity
• D. Synergism

Answer: (D)

When two agents interact to produce a combined effect that is greater than what you would expect by simply adding their separate effects, that interaction is synergism. This means the two work together in a way that boosts the overall impact beyond the sum of each one's independent action.

Think of it as a teamwork effect: neither alone might achieve a strong result, but together they produce a much larger effect. In contrast, an additive interaction would simply equal the sum of their individual effects, while antagonism would produce a smaller combined effect than expected. Potentiation is related but involves one agent enhancing the effect of another that may have little or no effect on its own.

A classic example is certain antibiotic combinations where one drug damages the bacterial cell wall and enables the other to enter more effectively, yielding a greater bacterial kill than either drug could achieve alone.