The correct option is A Tubulin The mitotic spindle is a highly dynamic molecular machine composed of tubulin, motors, and other molecules. It assembles around the chromosomes and distributes the duplicated genome to the daughter cells during mitosis.
Tubulin is the protein, which makes up microtubules. Microtubules are assembled from dimers of α- and β-tubulin. Each of these subunits has three domains. γ-tubulin is important in the nucleation and polar orientation of microtubule.
Humulin - used for a preparation of insulin produced by genetic engineering and structurally identical to insulin made by the human pancreas.
Intermediate filaments (IFs) are cytoskeletal components found in the cells of many animal species. They are composed of a family of related proteins sharing common structural and sequence features.
Flagellin is a globular protein that arranges itself in a hollow cylinder to form the filament in a bacterial flagellum.
Flagellin is the principal substituent of bacterial flagellum, and is present in large amounts on nearly all flagellated bacteria. So, the correct answer is option A.