A circuit has a resistance of 200?. The resistance of the circuit can be reduced to 120? when

When resistors are connected in series, their total resistance is equal to the sum of their individual resistances. Therefore, adding an 80Ω resistor in series with the 200Ω circuit will result in a total resistance of 280Ω. On the other hand, when resistors are connected in parallel, their total resistance is given by the formula: 1/R_total = 1/R1 + 1/R2 + 1/R3 + ... Therefore, adding a 300Ω resistor in parallel with the 200Ω circuit will result in a total resistance of: 1/R_total = 1/200 + 1/300 = 5/600 R_total = 600/5 = 120Ω Therefore, the correct option is "a 300Ω resistor is connected to it in parallel", which will reduce the resistance of the circuit from 200Ω to 120Ω.