In a psychological experiment, the potentially causal factor that is manipulated by the investigator is called the variable while the factor that may be influenced by the manipulated experimental treatment is called the variable.

Dependent and Independent variable

Explanation:

Independent variables are defined as those variable, that can be used in order to change or control an experiment, and this variables can directly cause impact on the dependent variable.

On the other hand, dependent variables can be defined as those variable that can be tested and also measured in a particular experiment. This variable is directly dependent on the independent variable.

In the given condition, mentioning a psychological experiment, the potentially casual factor that can be easily manipulated by an investigator can be considered as a dependent variable, whereas the factor that can be influenced by the manipulated experimental treatment can be referred to as the independent variable.

the first question's answer is a.