A conjoint and open vascular bundle will be observed in the transverse section of

A conjoint and open vascular bundle will be observed in the transverse section of dicot stem.

Vascular bundles are arranged in a ring in dicot stem.

Each vascular bundle is conjoint, open, and with endarch protoxylem.

Monocot stem has a large number of scattered vascular bundles. Here vascular bundles are conjoint and closed.

And open bundles are present only in pats where secondary growth is possible and only dicot stem is capable of secondary growth.

Hence the correct answer is option (d).