Answer:
Force per unit charge on a positive test charge
Step-by-step explanation:
There exist a force between two charged particles as per Coulomb's law. It states that the force is directly proportional to the product of charges and inversely proportional to the square of distance between them. It is given by :

Where, q is positive test charge
Q is source charge
The area surrounded by electric charge is called electric field. It is defined as the electric force acting per unit charge.

or

Hence, the statement that defines an electric field is " Force per unit charge on a positive test charge ".