If x is amount of adsorbate and m is amount of adsorbent, which of the following relations is not related to adsorption process ?

Question

( A ) $p = f(T)$ at constant $(\frac{x}{m})$
( B ) $\frac{x}{m} = p \times T$
( C ) $ \frac{x}{m} = f(p)$ at constant $T$
( D ) $\frac{x}{m} = f(T)$ at constant $p$