d
since the two equations are of the form, $\ln P+m \ln V=C$
Hence, $P V^{m}=$ constant
Thus, slope of the graph is equal to $\gamma$
$\gamma=\frac{f+2}{f}=1+\frac{2}{f}$
since $\gamma_{1}>\gamma_{2},$ thus $f_{2}>f_{1}$
since $C_{V}=\frac{f}{2} R,$ thus $C_{V_{2}}>C_{V_{1}}$
Answer is $\mathrm{B}, \mathrm{C}$