Companion cells are closely associated with

Companion cells are thin-walled cells found in:

The leaves of $Victoria \text{ } regia$ are rigid due to the presence of:

......... occurs in layers below the epidermis in dicotyledonous plants.

Mechanical tissue is best developed in

The first formed primary phloem is referred to as $A$. The later formed primary phloem is referred to as $B$. Choose the correct combination of $A$ and $B$.