Step 1: Analyzing the circuit.
The circuit consists of an OR gate followed by a NOT gate (inverter). The OR gate gives the output \( A + B \), and the NOT gate inverts the output to produce \( \overline{A + B} \).
Step 2: Boolean expression.
The output of the circuit is given by the expression \( A + B \), and the NOT gate inverts it. The final Boolean expression is \( A + B \).
Step 3: Conclusion.
The correct Boolean expression is \( A + B \), corresponding to option (A) OR gate.