Question

the passage below describes an experiment.
preston works at a bakery. after making the bread dough one morning, preston left the dough on a counter to rise. after three hours, the dough doubled in size. preston wondered if leaving dough someplace warmer could make the dough rise faster. preston then made some dough and divided it into six equal portions. he put three of the portions of dough on the counter. he put the other three portions near a sunny window where it was warmer. he checked how much each portion of dough rose after one hour.
in this experiment, the portions of dough left on the counter were part of ____.
a control group an experimental group

Explanation:

In an experiment, a control group is the group that is not exposed to the independent variable (in this case, the warmer temperature near the sunny window) and is used for comparison. The dough on the counter is kept under the original, non - warmer condition, so it serves as the control group to compare with the dough near the sunny window (experimental group) which is exposed to the warmer temperature.

Answer:

a control group