Question

______ is the stage of mitosis in which chromosomes uncoil and spindle fibers break down.

Explanation:

In mitosis, the stage where chromosomes uncoil (decondense) and spindle fibers break down is telophase. During telophase, the separated chromosomes reach the poles, start to uncoil back into chromatin, and the spindle apparatus disassembles.

Answer:

Telophase