Step 1: Plan
The amount of gas is fixed, so $PV/T$ stays constant.
Step 2: Substitute
$P_2 = \dfrac{P_1 V_1 T_2}{T_1 V_2} = \dfrac{1 \times 5 \times 500}{300 \times 2} = \dfrac{2500}{600}$.
Step 3: Result
$2500/600 = 4.17$, which matches the given 4.16 atm. Ignoring T (Boyle only) would give 2.5 atm, so (C) is a trap.
Final Answer:
Option (D), 4.16 atm.
\[ \boxed{4.16 \text{ atm}} \]