The Discrepancy Model of Loneliness Suggests That Intensity of Loneliness

The discrepancy model of loneliness suggests that intensity of loneliness is a function of the difference between:

A) the actual level and the desired level of social contact.
B) the level of social contact that the person biologically needs and what he/she achieves.
C) the level of social contact and one's attachment style.
D) All of these.