Parallel resistor reduces shunting in potential divider Steps:

• Potential divider has upper resistor R1 and lower fixed resistor R2, with variable R parallel to R2.
• Effective lower resistance R_eff = (R2 × R) / (R2 + R); as R increases, R_eff increases toward R2.
• Total resistance rises, but voltage fraction across lower arm R_eff / (R1 + R_eff) increases.
• Voltmeters V1 (across R2) and V2 (across R) both measure this increasing lower-arm voltage.

Why B is correct:

• Both V1 and V2 read the potential difference across the parallel lower section, which rises per the voltage divider formula as shunting decreases.

Why the others are wrong:

• A: Voltages increase, not decrease, due to higher R_eff fraction.
• C: V2 increases with the lower-arm voltage, does not decrease.
• D: V1 increases like V2, does not decrease.

Final answer: B