For the circuit shown, if R3 opens, the voltage at point A will decrease. stay the sameincrease.

To determine the effect of opening R3 on the voltage at point A, we need to analyze the circuit.

1. First, let's identify the components in the circuit. We have resistors R1, R2, and R3, and a voltage source connected to point A.

2. When R3 opens, it means that the circuit is broken at that point, and no current can flow through it.

3. Since no current can flow through R3, it effectively becomes an open circuit, and the current path is interrupted.

4. As a result, the current flowing through the circuit will be affected. Without current flowing through R3, the total resistance in the circuit will increase.

5. According to Ohm's Law (V = IR), if the resistance increases and the current decreases, the voltage across the resistors will also change.

6. In this case, since R3 is in series with the voltage source and point A, the voltage at point A will decrease when R3 opens.

Therefore, the correct answer is that the voltage at point A will decrease if R3 opens.