The correct option is B Red blood cell
Viruses are not plants, animals, or bacteria, but they are the parasites of the living kingdoms. Although they may seem like living organisms because of their reproductive abilities, viruses are not living organisms in the strict sense of the word. They use the host machine to reproduce. Premature RBCs have a nucleus, ribosomes, mitochondria, etc and produce all the required structural and functional proteins. On maturing they loose the nucleus and cell organelles and contain only haemoglobin in their cytoplasm.