Using the canonical equations, what is $x$ and $Y$ :

$\frac{\text{d}\text{e}\text{l}\text{x}}{\text{d}\text{e}\text{l}\text{Y}}=(T,p,n)$

$\frac{\text{d}\text{e}\text{l}\text{x}}{\text{d}\text{e}\text{l}\text{Y}}=(T,V,n)$

$\frac{\text{d}\text{e}\text{l}\text{x}}{\text{d}\text{e}\text{l}\text{Y}}=S(T,p,n)$