Collenchyma provides mechanical support while remaining alive at maturity, whereas sclerenchyma dies once its secondary wall forms. What functional consequence follows from keeping a supporting cell alive?

C. It can stretch and expand as the surrounding organ elongates

Lignified sclerenchyma cannot expand once set, making it unsuitable for growing tips. Retaining a living protoplast allows collenchyma to remodel its primary wall during elongation. Active transport in plumbing belongs to phloem, and post-injury cell division is the domain of unspecialised parenchyma.