24. A 30 -ohm resistor and a 60 -ohm resistor are connected as shown above to a battery of emf 20 volts and internal resistance r. The current in the circuit is 0.8 ampere. What is the value of r ?
A) 0.22Ω
B) 4.5Ω
C) 5Ω
D) 16Ω
E) 70Ω