Mark the correct sequence of layers found in root anatomy.

In exarch xylem,the development of xylem is:

Casparian strips are present in the ........

$A$: According to Clowes,there are three histogens in monocot root.
$R$: In dicot roots,innermost groups of initials form root cap.

Given below are two statements:
Statement $I:$ Endarch and exarch are the terms often used for describing the position of secondary xylem in the plant body.
Statement $II:$ Exarch condition is the most common feature of the root system.
In the light of the above statements,choose the correct answer from the options given below:

You are given a fairly old piece of dicot stem and a dicot root. Which of the following anatomical structures will you use to distinguish between the two?