20) C


A is a measure of electrical power.
P = VI
I = Q / t
Substituting (I = Q / t) in the equation P = VI,
P = (Q / t) x V = QV / t

B is a measure of electrical power. 
P = IV
V = IR
Substituting (V = IR) in the equation P = VI,
P = I x IR = I²R

C is not a measure of electrical power. 
There is no way to equate P = (Q²R / t)

D is a measure of electrical power. 
P = VI is the most basic formula for power and it something that needs to be learnt.

E is a measure of electrical power. 
P = IV
I = V / R
Substituting (I = V / R) in the equation P = VI,
P = V x (V / R) = (V² / R)