Which phase of mitosis is characterized by each pair of sister chromatids moving to opposite sides of the cell?

A. prophase
B. metaphase
C. telophase

B. metaphase

The phase of mitosis characterized by each pair of sister chromatids moving to opposite sides of the cell is called metaphase. To arrive at this answer, first, let's understand the process of mitosis.

Mitosis is the process through which cells divide and create two identical cells, each with a complete set of chromosomes. It consists of four main phases: prophase, metaphase, anaphase, and telophase.

During prophase, the chromosomes condense, becoming more visible, and the nuclear envelope dissolves. The spindle fibers begin to form.

Metaphase is the next phase. During metaphase, the pairs of sister chromatids align themselves along the equator of the cell. This line in the middle is called the metaphase plate. The spindle fibers attach to the centromeres of the chromosomes and play a vital role in moving the chromosomes.

In anaphase, the sister chromatids separate and are pulled to opposite sides of the cell by the spindle fibers. This results in two distinct sets of chromosomes.

Finally, during telophase, the nuclear envelope reforms around the separated chromosomes, and the spindle fibers disassemble. The cell prepares for cytokinesis when it will physically divide into two separate cells.

Therefore, the correct answer to your question is B. metaphase, as it is the phase when each pair of sister chromatids move to opposite sides of the cell.