imbibition process involves
a both diffusion and capillary action
b only diffusion
c only capillary action
d none

Dear student, 
​Please find below the solution to the asked query        

Imbibition is a type of diffusion in which there is adsorption of water or any other liquid by the solid particles of a substance without forming a solution. In imbibition the molecules of water or any other liquid (i.e. imbibate) are held in between or over the surface of solid substances (i.e. imbibants) through the process of capillarity or by the force of adsorption (i.e. sticking to the surface). 
Imbibition involves both diffusion and capillary action. Hence, option (a) is correct.

Hope this information will clear your doubts about the topic.    Regards