Which among the following is incorrect about different cells in Phloem?

• A. Sieve tubes are tubular cells with perforated walls with large vacuoles, peripheral cytoplasm and without nucleus
• B. Companion cells are specialized parenchyma cells that help in regulation of metabolic activities
• C. Phloem parenchyma cells are elongated cylindrical cells that support sieve tubes
• D. Phloem fibers are living cells with extremely thick cell walls and provide mechanical strength