The roots of a plant are usually located underground and composed of which of the following tissue systems?

This question is incomplete as it should have provided a choice of different tissue systems. I think the answer is a thin continuous cylinder made up of meristematic cells located between the wood (secondary xylem) and bark (secondary phloem) of roots and stems. The meristematic cells divide and add to the wood and inner bark. 

The tissues of a plant are organized into three tissue systems:

1.     the dermal tissue system

2.     The ground tissue system.

3.     The vascular tissue system.

The roots of a plant are usually located underground and composed of Ground Tissues. Roots are present in a central column.

It is a thin continuous cylinder made up of Meristematic cells located between the wood (secondary xylem) and bark (secondary phloem) of roots and stems called in a central column. The Meristematic cells divide and add to the wood and inner bark.

Could you attach an image of the table ?

Yes yes yes very good