Biology

The correct answer is A.whether there is a predator or not.

In this experiment, the independent variable is whether there is a predator or not, because this is the factor being manipulated to observe how it affects the fish's behavior (whether they school more or not).

Here's why the other options are not correct:

B.Number of fish school together: This is the dependent variable, as it is the outcome being measured in response to the presence or absence of a predator.