Correct Answer: D
Explanation:
Ribosomes are minute cellular, non-membranous particles having an average diameter of 23 mm (230 A0).
In plant cells ribosomes were first of all observed by Robinson and Brown (1953) in bean roots. In animal cells, these were discovered by Palade (1955), hence are called Palade particles. Ribosomes form a part of fraction microsome, a term given by A, Claude (made of broken ER, ribosomes and Golgi bodies).