Why are stone cells found in pears and not in berries?
a. stone cells are only found in fruits with peels and berries don't have peels
b. stone cells protect seeds and pears have more seeds than berries
c. stone cells are only found in fruit that grows on trees and most berries grow on bushes
d. stone cells make fruit firm and berries are softer than pears

D. stone cells make fruit firm and berries are softer than pears

Explanation:

Stone cells are also called sclereids and are the short cells with thick lignified walls. Mature stone cells do not have any living content. Due to their lignified wall, stone cells make the plant part hard and gritty. Since berries are the soft and fleshy fruits, they do not have stone cells. Pears have gritty flesh due to the presence of stone cells in small clusters in it.