The bulk of a leaf consists of mesophyll, which is photosynthetic ____ with air spaces between cells.

A) collenchyma
B) parenchyma
C) sclerenchyma
D) phloem
E) xylem

Mesophyll is made up of parenchyma cells which are responsible for photosynthesis, and the air spaces between cells allow for gas exchange during photosynthesis. Collenchyma and sclerenchyma cells are structural cells that provide support to the plant, while phloem and xylem are vascular tissues involved in transport.