The below graph shows the behaviour of 3 gases undergoing adiabatic expansion. Which of the following can be true?

Question

$\begin{array}{1 1} \text{gas1:diatomic, gas2: triatomic, gas3: monoatomic} \\ \text{gas1:triatomic, gas2: diatomic, gas3: monoatomic} \\ \text{None of these } \\ \text{gas1: monoatomic, gas2: diatomic, gas3: triatomic} \end{array}$