Name all the possible combinations that form a ray, in the figure below:

A ray is a portion of a line. It starts at one point and goes endlessly in a direction. 

In the given figure,

The possible rays are:

$\overrightarrow{\mathrm{AD}}, \overrightarrow{\mathrm{DA}}, \overrightarrow{\mathrm{FC}}, \overrightarrow{\mathrm{CF}}, \overrightarrow{\mathrm{ED}}, \overrightarrow{\mathrm{EF}}, \overrightarrow{\mathrm{DF}},\overrightarrow{ \mathrm{FD}}$.