Final answer:
The term 'protosomes' does not correspond to any recognized biological entity in the context of ribosomes or protein synthesis. It is likely this term is a typo or misunderstanding in the question. Ribosomes are cellular structures made of rRNA and proteins, crucial for protein synthesis.
Step-by-step explanation:
The term 'protosomes' is not directly related to ribosomes or protein synthesis, as given in the options provided by the question.
None of the definitions presented match any known biological structures or processes, so it appears there may be a misunderstanding or typo in the original question.
However, ribosomes, which are related to the options given, are essential cellular structures responsible for protein synthesis.
They consist of two subunits both made of rRNA and protein. Ribosomes can be found freely in the cytoplasm or attached to the endoplasmic reticulum and are vital for translating mRNA into a specific sequence of amino acids to form proteins.