**Core Concept**
The 'Orphan-Annie eye' nucleus refers to a characteristic appearance of the nucleus in certain cells, specifically seen in the context of certain pathologies. This term is used to describe the appearance of the nucleus in cells that have undergone degenerative changes.

**Why the Correct Answer is Right**
The 'Orphan-Annie eye' nucleus is typically seen in cells that have undergone degeneration due to viral infections, such as herpes simplex virus (HSV). The nucleus appears as a small, empty space or 'eye' with a surrounding halo of condensed chromatin. This is due to the viral replication process, which causes the nucleus to shrink and the chromatin to be pushed to the periphery.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the 'Orphan-Annie eye' nucleus is not typically associated with bacterial infections, such as those caused by Streptococcus or Staphylococcus species.

**Option B:** This option is incorrect because the 'Orphan-Annie eye' nucleus is not a characteristic feature of normal or healthy cells.

**Option C:** This option is incorrect because the 'Orphan-Annie eye' nucleus is not typically associated with fungal infections, such as those caused by Candida or Aspergillus species.

**Clinical Pearl / High-Yield Fact**
The 'Orphan-Annie eye' nucleus is a classic example of a cytopathic effect caused by viral infections, and it is an important diagnostic clue in the identification of certain viral pathogens. It is essential for clinicians and pathologists to recognize this feature to make an accurate diagnosis.

**Correct Answer:** D.