Choose the correct statement for processes $A$ and $B$ shown in the figure.

• A
  $PV^\gamma = k$ for process $B$ and $PV = k$ for process $A$.
• B
  $PV = k$ for process $B$ and $A$.
• C
  $\frac{P^{\gamma-1}}{T^\gamma} = k$ for process $B$ and $T = k$ for process $A$.
• D
  $\frac{T^\gamma}{P^{\gamma-1}} = k$ for process $A$ and $PV = k$ for process $B$.