Answer: Sieve tube elements.
- A Sieve tube elements
- B Companion cells
- C Xylem vessels
- D Sclereid fibres
Correct answer: A. Sieve tube elements
Explanation: Mature sieve tube elements stay alive to conduct food but lack a nucleus; their companion cells keep theirs and support them.
Concept context
Internal tissue organisation: meristems, permanent tissues (xylem, phloem, parenchyma), and secondary growth. Frequently tested in NEET.