Answer: c
Explanation: Spindle fiber: is a microtubules that comes out from the centrosomes when the cell is preparing for division. They are responsible for the segregation of sister chromatids and movement of chromosomes during mitotic and meiotic division.
Flagella: a slender threadlike structure, especially a microscopic appendage that enables many protozoa, bacteria, spermatozoa, etc. to swim.
The thread-like structure is called chromosomes.
This can conclude that microtubules are common in spindle fiber and flagella.