During mitosis, what is the primary role of spindle fibers (microtubules) in the dividing cell?

• A. They form the cleavage furrow that pinches the cell into two during cytokinesis.
• B. They attach to kinetochores and separate sister chromatids by pulling them toward opposite poles of the cell.
• C. They replicate the cell’s DNA to ensure each daughter cell receives a complete genome.
• D. They break down the nuclear envelope by enzymatically digesting nuclear lamins.

Answer: (B)