Dead cells with narrow lumen, lignified cell wall with a few or numerous pits and serving a mechanical function only are called -
Collenchyma
O
Xylem
O
Aerenchyma
O
Sclerenchyma

The correct answer is - Sclerenchyma

Explanation:

Sclerenchyma  are the dead cells with narrow lumen lignified cells. These dead cells has numerous pits that helps in trading the various substances to neighboring cells. At matuarity, hese cell lack the protoplast so therefore called dead cells .

Sclerenchyma cells are lignified which makes them thick and these cells help in the supporting the plants. These cells are impereable to almost everything gases, substances and many more.

not too sure maybe olecranon process

answer; i believe the correct answer is ( proteins );