Assertion ($\mathrm{A}$): The veins vary in thickness in dicot leaves, with reticular venation.

Reason ($\mathrm{R}$): The size of the vascular bundles is dependent on the size of the veins.

Identify the labelled parts as $1, 2, 3, 4, 5$ of the water movement in a leaf shown in the figure ?

Assertion ($\mathrm{A}$): The veins vary in thickness in dicot leaves, with reticular venation.

Reason ($\mathrm{R}$): The size of the vascular bundles is dependent on the size of the veins.

Assertion ($\mathrm{A}$): The spring wood has a greater number of Xylem vessels with wider lumens.

Reason ($\mathrm{R}$): During the spring season plant requires a large amount of water mineral salts.

The dendrochronology is based on $\underline{ }$