Using the mirror equation, 1/f = 1/do + 1/di, where f is the focal length, do is the object distance, and di is the image distance.
Plugging in the values, we get:
1/8 = 1/3 + 1/di
Simplifying the equation, we get:
1/di = 1/8 - 1/3
1/di = (3 - 8)/24
1/di = -1/24
di = -24 cm (Note: the negative sign indicates that the image is virtual)
Therefore, the image distance of the object is 24 cm, which corresponds to option 1: -2.18 cm, as the image distance is negative, indicating a virtual image.