Anaphase and S-phase are two distinct phases of the cell cycle where the number of chromosomes and the amount of DNA content per cell undergo changes.

Anaphase:
- In the cell cycle, anaphase is the stage that follows metaphase.
- During anaphase, the sister chromatids of each chromosome separate and move towards opposite poles of the cell.
- This separation is facilitated by the shortening of microtubules attached to the chromatids, which pull them apart.
- As a result of this separation, the number of chromosomes in the cell doubles temporarily.
- For example, if the cell initially had 46 chromosomes, during anaphase, it would have 92 chromosomes.
- However, it is important to note that these chromosomes are not identical to the ones present in the initial cell. They are sister chromatids that will eventually become individual chromosomes in the daughter cells.

S-phase:
- S-phase is a stage of interphase, which is the longest phase of the cell cycle.
- During S-phase, DNA replication occurs, leading to the duplication of the cell's genetic material.
- Each chromosome is replicated, resulting in the formation of two identical sister chromatids held together by a centromere.
- As a result of DNA replication, the amount of DNA content per cell doubles.
- For example, if the cell initially had 2N DNA content, after S-phase, it would have 4N DNA content.
- This doubling of DNA content is necessary to ensure that each daughter cell receives a complete set of genetic material during cell division.

Comparison:
- Both anaphase and S-phase involve changes in the number of chromosomes and the amount of DNA content per cell.
- However, the changes in anaphase are temporary and occur due to the separation of sister chromatids, while the changes in S-phase are permanent and result from DNA replication.
- Anaphase leads to a temporary doubling of the number of chromosomes, while S-phase leads to a permanent doubling of the amount of DNA content.
- Therefore, the correct answer is option 'A' - anaphase and S-phase.