Name a cell organelle found only in a plant cell.(a)Plastid(b)Chromosome(c)Ribosome(d)None of the above

The question asks for a cell organelle that is found only in a plant cell. Let's analyze the options provided:

(a) Plastid: This is the correct answer. Plastids are organelles found in the cells of plants and some algae. They are involved in the synthesis and storage of food. The most common type of plastid is the chloroplast, which is responsible for photosynthesis.

(b) Chromosome: Chromosomes are found in both plant and animal cells. They contain genetic material and are not exclusive to plant cells.

(c) Ribosome: Ribosomes are found in all types of cells, including prokaryotic and eukaryotic cells, and are involved in protein synthesis. They are not exclusive to plant cells.

(d) None of the above: This option is incorrect because option (a) is a valid answer.

Therefore, the correct answer is (a) Plastid.