One of the most unusual aspects of virus particles is the absence of all organelles and other smaller structures. whereas cells have many kinds of organelles, viruses consist of only two parts: a nucleic acid core made of dna or rna, and a tough, potective protein shell. which name is given to this tough shell made of protein? a) capsid b) acrosome c) endospore d) lytic layer

The tough shell made of protein of the viruses is called capsid (Solution A). The protomers are the subunits if this shell, which are made of protein. The structure of the capsid is either helical or icosahedral.
When a virus infects a cell it begins to replicate itself  and during this process new subunits (new protomers) are synthesized according to the genetic material of the virus.