The correct option is (c).
Explanation
Phloem is a complex permanent tissue in vascular plants responsible for the translocation of organic nutrients (food), particularly sucrose, from the leaves to other parts of the plant. Unlike xylem, which conducts water and minerals, phloem transports food materials usually in both directions (bidirectional flow).
Statement-wise Analysis
- Statement 1 is Incorrect. Phloem is composed of four main types of elements: sieve tube elements, companion cells, phloem parenchyma, and phloem fibres. Tracheids, vessels, and xylem parenchyma are components of Xylem tissue, not Phloem.
- Statement 2 is Correct. Among the four elements of phloem, sieve tube elements, companion cells, and phloem parenchyma are living cells. Phloem fibres (also known as bast fibres) are sclerenchymatous cells and are the only dead cells in the phloem tissue at maturity. They provide mechanical support.
- Statement 3 is Correct. Sieve tubes are long, tubular conducting channels formed by end-to-end fusion of sieve tube elements. Their end walls are perforated in a sieve-like manner to form sieve plates, which allow the passage of food materials.
Key Takeaway
Phloem consists of sieve tubes, companion cells, phloem parenchyma (all living), and phloem fibres (dead). Xylem consists of tracheids, vessels, xylem fibres (all dead), and xylem parenchyma (living).