Question

1. a controlled experiment allows the scientist to isolate and test *

1 point
a large amount of information
a conclusion
several variables
a single variable

Explanation:

In a controlled experiment, the key is to isolate and test one variable at a time while keeping other factors constant. This helps in determining the effect of that specific variable. A controlled experiment is not about testing a large amount of info (first option), a conclusion is drawn from results (second), and it's not several variables (third) as that would confound results. So the correct choice is testing a single variable.

Answer:

D. a single variable