For $1 \text{ mole}$ of an ideal gas expanding isothermally from $1 \text{ L}$ to $10 \text{ L}$ at $300 \text{ K}$,the value of $\Delta U$ is: $(R = 2 \text{ cal mol}^{-1} \text{ K}^{-1})$

• A
  $163.7 \text{ cal}$
• B
  $0 \text{ cal}$
• C
  $1381.1 \text{ cal}$
• D
  $9 \text{ L-atm}$