Answer: Option A. "Cytoskeleton"
Step-by-step explanation:
Cytoskeleton can be defined as the network of protein filaments in the cytoplasm eukaryotic cells interlinking from cell nucleus to cell membrane.
There are three basic types of protein fibers present in cytoskeleton that includes micro filaments (Actin filaments ), microtubules and intermediate filaments.
Microfilaments are consist many linked monomers of a protein known as actin, that combines in a double helix with a diameter of about 7 nano-meter and functions as serving tracks for myosin (motor protein).
Microtubules are arranged in a form of hollow straw like structure made up of consist of tubulin proteins having diameter of about 25 nano-meter and further consist of two subunits, α-tubulin and β-tubulin.
Intermediate filaments are the cytoskeletal element which are made up of multiple strands of fibrous proteins wounded together having an average diameter of 8 to 10 nano-meter.