Static Electricity - Mission SE10 Detailed Help

A charge Q creates an electric field. A test charge q is used to measure the strength of the electric field at a distance d from Q. The force F is experienced by the test charge q. The electric field strength at this location is given by the expression ___. List all that apply ... .

Definition of Electric Field Strength:
Any source of charge Q will create an electric field in the space surrounding it. The strength of an electric field (E) at any given location in this space can be determined by placing a test charge q in the space and measuring the force (F) that is exerted upon it. The electric field strength is defined as the amount of force per unit of charge on the test charge. 

E = F / q

The electric field strength (E) is defined as the amount of force exerted upon a test charge per unit of charge on the test charge (q). That is, 
E = F / q.

The electric force (F) depends upon a number of variables as described by Coulomb's law: 
Felect= k • Q1• Q2/ d2
In the above equation, Q1 might be the source charge Q and Q2 might be the test charge q. If the expression for force as given by the Coulomb's law equation is substituted in for F in the electric field strength equation, then the equation for electric field becomes
E = k • Q / d2