Which of the following is less than zero during adsorption?

Adsorption is process where randomness decreases and energy is released. Hence, $\text{\Delta S}$ will be negative (as randomness is decreasing)$and \text{\Delta H}$ will also be negative ($\text{\Delta H}$ is negative for exothermic processes).
Depending on the values of Entropy and enthalpy, the Gibbs energy can either be negative or positive.