Which phase of cell division involves the formation of the nuclear envelope?

The formation of the nuclear envelope occurs during the telophase of cell division. At this stage, the separated chromosomes, which were pulled apart during anaphase, begin to de-condense back into chromatin. As the cell prepares to divide into two daughter cells, the nuclear envelope re-forms around each set of chromosomes, creating two distinct nuclei within the cell. This re-establishment of the nuclear envelope is essential for creating a proper environment for the genetic material in each new cell.

In contrast, prophase is characterized by the condensation of chromatin into visible chromosomes and the breakdown of the nuclear envelope, while anaphase involves the separation of sister chromatids moving toward opposite poles of the cell. Metaphase is when chromosomes are aligned along the equatorial plane of the cell, and the nuclear envelope is not present during this stage. Therefore, telophase uniquely marks the point at which the nuclear envelope re-forms, making it the correct answer.