Separate ideal gas

In the above left container, there is an monatomic ideal gas with number of molecules, pressure and internal energy, $n, P$ and $U,$ respectively. Now, as in the above right, we separate the container into two equal parts by a divider. Which of the following explanations is correct about the ideal gas $A?$

$R$ denotes the ideal gas constant.

a) The internal energy of $A$ is $\displaystyle \frac{U}{2}.$
b) The volume of $A$ is $\displaystyle \frac{U}{3P}.$
c) The absolute temperature of $A$ is $\displaystyle \frac{U}{3nR}.$