Final answer:
The most abundant and least specialized plant cell is the parenchyma cell, known for its roles in photosynthesis, wound healing, and starch storage.
Step-by-step explanation:
The most abundant and least specialized plant cell is the parenchyma cell. Parenchyma cells are versatile and are found throughout various parts of a plant, including the stem, root, inner parts of the leaf, and the fruit pulp. These cells play a pivotal role in metabolic functions such as photosynthesis, as well as in the repair and healing of wounds. They also often serve as storage centers for starch. In contrast to Student A's report of meristematic cells, Student B's tally of mostly collenchyma cells, and Student C's observation of sclerenchyma cells, it is Student D's observation that aligns with the recognition of parenchyma cells as the most common type of plant cell.