Question

1. addition in toxicology refers to:

two drugs effects summing exactly to individual effects
taking extra doses for fun
biological tolerance
psychological dependence

Explanation:

In toxicology, addition (or additive effect) occurs when the combined effect of two drugs is equal to the sum of their individual effects. Let's analyze the options:

• "Psychological dependence" is about mental reliance on a drug, not related to toxicological addition.
• "Biological tolerance" refers to the body's reduced response to a drug over time, not about interaction of two drugs.
• "Taking extra doses for fun" is about drug misuse, not a toxicological concept of addition.
• "Two drugs’ effects summing exactly to individual effects" matches the definition of additive effect in toxicology.

Answer:

The correct option is the one with "Two drugs’ effects summing exactly to individual effects" (the fourth option, though the identifier isn't fully clear from the image, the text option is "Two drugs’ effects summing exactly to individual effects").