The correct option is B tubulin
Microtubules are polymers of tubulin protein. They are cytoskeletal components that provide structural framework to the cell. They also play a major role during mitosis by forming spindle fibres that attach to chromosomes and pull the chromatids apart.
Actin and myosin are proteins that help during muscle contraction.
Condensins are proteins that play a key role in mitotic chromosomes assembly and segregation.