Step 1: Isothermal (A)
\(P_AV=P_A\cdot\frac V2\) gives \(P_A=2P\).
Step 2: Adiabatic (B)
\(PV^\gamma=P_B\left(\frac V2\right)^\gamma\) gives \(P_B=2^\gamma P\).
Step 3: Compare
Since \(\gamma>1\), \(2^\gamma>2\), so \(P_B>P_A\). Option (A).
Final Answer:
\(P_A<P_B\), option (A).
\[ \boxed{\text{(A)}} \]