Oil rises up to wick in a lamp because_____________?

A. Oil is very light
B. Oil is volatile
C. Diffusion of oil through the wick
D. Capillary action phenomenon

Capillary action (sometimes capillarity, capillary motion, capillary effect, or wicking) is the ability of a liquid to flow in narrow spaces without the assistance of, or even in opposition to, external forces like gravity