Question

a farmer wants to improve crop yield in his fields by testing the effectiveness of a new pesticide available on the market. which of the following is the best control for this experiment?

no new pesticide used on the control field; new pesticide used only on the experimental field

more shade on the control field than the experimental field

less new pesticide used on the control field than the experimental field

more water on the control field than the experimental field

Explanation:

A control group in an experiment should differ from the experimental group only by the variable being tested (here, the new pesticide). All other conditions (water, shade, etc.) must be identical. The only option that isolates the pesticide as the single variable is using no new pesticide on the control field while using it on the experimental field.

Answer:

no new pesticide used on the control field; new pesticide used only on the experimental field