Answer:
An organ
Step-by-step explanation:
An organ can be defined as a collection of similar types of tissue which perform the similar perfect function. The main function of the root is to collect nutrients and water from the soil.
As a result of this the root are modified in such a way that their surface area is increased and are modified in a way so that they can observe water in a better way. This is done by change in the molarity of the solution which are present in the root hair cells.