The correct answer is option D) M.

Interphase is the longest phase of the cell cycle, and it consists of three distinct phases: G1, S, and G2. During interphase, the cell grows, replicates its DNA, and prepares for cell division.

- **G1 phase**: This is the first phase of interphase, and it stands for "Gap 1" or "growth 1." In this phase, the cell grows in size, synthesizes proteins necessary for cell division, and carries out its normal functions. The duration of the G1 phase varies among different cell types and can even be extended indefinitely in some cells, leading to a non-dividing state called G0.

- **S phase**: The S phase stands for "Synthesis." In this phase, the cell replicates its DNA by undergoing DNA synthesis or replication. Each chromosome is replicated to form sister chromatids, which are held together by a structure called the centromere.

- **G2 phase**: The G2 phase, also known as "Gap 2" or "growth 2," follows the S phase. During this phase, the cell continues to grow and prepares for cell division by synthesizing proteins required for mitosis or meiosis. The cell checks its DNA for errors and repairs any damage before entering the next phase.

- **M phase**: The M phase stands for "Mitosis" or "Meiosis," depending on whether the cell is undergoing mitotic or meiotic division. This phase involves the actual division of the cell's genetic material and the subsequent formation of two daughter cells.

Therefore, the M phase is not a part of interphase. It is a distinct phase that follows interphase and involves the division of the cell's genetic material.