Final answer:
The junctional epithelium in a healthy individual typically has a length ranging from 0.25 to 1.35 millimeters, option D.
Step-by-step explanation:
In health, the length of the junctional epithelium ranges from typically 0.25-1.35mm. This cellular structure plays a vital role in dental health by adhering the gingiva to the tooth, which protects the underlying structures. Junctional epithelium is a type of non-keratinized epithelial tissue that forms the base of the sulcus and is attached to the tooth surface.
Answering the student's question directly: the length of junctional epithelium in health ranges from D. 0.25-1.35mm.