A biologist was in a forest when he came across a family of squirrels hiding nuts for

the winter. The biologist was interested in this behavior, so he stayed and watched the

squirrels for a few hours. He recorded what he observed in a notebook. Which of the

following explains why this type of research is NOT considered an experiment?

O The biologist did not observe the squirrels for long enough to collect data.

The biologist did not collect valid data on the different species of squirrels present.

O The biologist observed the squirrels and did not test variables.

O The biologist came across the squirrels by chance and had no formal plan.