Dr Hartwick Wants to Determine If a Group of Participants

Dr. Hartwick wants to determine if a group of participants reading under incandescent light will read more pages of text in one hour than a group of participants reading under fluorescent light. She assigns students sitting at the front of the class to be in the "incandescent light"condition and students at the back of the class to be in the "fluorescent light"condition. In this experiment seating location is

A) the independent variable.
B) the dependent variable.
C) a confounding variable.
D) a valid variable.
E) an operational definition.