$3.$ What is the main difference between adsorption and absorption$?$

$-$ A$.$ Adsorption occurs in gases, absorption occurs in liquids.

$-$ B$.$ Adsorption involves surface phenomena, absorption involves volume phenomena.

$-$ C$.$ Adsorption requires a catalyst, absorption does not.

$-$ D$.$ Adsorption is an exothermic process, absorption is endothermic.