Question

a researcher conducts an experiment on worms. she is testing to see how the amount of caffeine affects the heart rate of a worm. she gives one group of worms 3ml of caffeine, another group of worms 6ml of caffeine and
the researcher did not accurately calculate the average heart rate.
the researcher had multiple independent variables.
the researcher did not include a control group.
the researcher gave different amounts of caffeine to each group of worms.

Explanation:

In a proper experiment, a control group is needed to compare the effects of the independent variable (caffeine amount). Here, the researcher only has groups with different amounts of caffeine and no group with no caffeine (control group) to determine if the changes in heart - rate are due to caffeine or other factors.

Answer:

The researcher did not include a control group.