Vascular bundles with cambium are called ___________.
If vascular bundles are containing the cambium in between xylem and phloem. It is called open vascular bundles, and it presents in dicots. If vascular bundles do not have cambium in between the xylem and phloem, then it is called as closed vascular bundles. In endarch, the protoxylem is directed towards the centre, whereas in exarch the protoxylem is directed towards the periphery.
So, the correct answer is 'Open' i.e. B.