Question

what factor can decrease the effectiveness of enzymes?
temperature
physical activity
aqueous solution

Explanation:

Enzyme effectiveness is affected by temperature. Extreme temperatures (too high or too low) can change the enzyme's structure (like denaturing at high temps) or reduce molecular motion, decreasing its ability to catalyze reactions. Physical activity doesn't directly impact enzyme effectiveness in a typical biochemical context, and aqueous solutions are the normal environment for many enzymes (they need water, so it doesn't decrease effectiveness).

Answer:

temperature