Correct option (d) position of protoxylem
Explanation
In dicotyledonous root, the condition of xylem is exarch as the protoxylem is away from the centre and metaxylem is towards the centre. In dicotyledonous stem. (e.g. Cucurbita), the condition of xylem is endarch as the metaxylern is away from the centre and protoxylem is towards the centre.