- A Sieve tubes and companion cells, both metabolically active
- B Vessels, tracheids, xylem fibres, and xylem parenchyma
- C Only vessels, with no tracheids or fibres present
- D Vessels and sieve tubes combined within one tissue type
Correct answer: B. Vessels, tracheids, xylem fibres, and xylem parenchyma
Explanation: Xylem has four components: (1) Vessels - wide tubes for water conduction; (2) Tracheids - narrow cells for water conduction and support; (3) Xylem fibres - mechanical support; (4) Xylem parenchyma - storage and lateral transport.
Concept context
Internal tissue organisation: meristems, permanent tissues (xylem, phloem, parenchyma), and secondary growth. Frequently tested in NEET.