**Core Concept**
Bacterial "finger printing" refers to the process of identifying and distinguishing between different bacterial strains based on their unique genetic or molecular characteristics. In the context of periodontal pathogens, this concept is used to understand the transmission and spread of these bacteria within and between individuals.

**Why the Correct Answer is Right**
The correct answer, "Transmissible within members of the same colonies," highlights the concept of bacterial clonal expansion, where a single bacterial cell can give rise to a large population of genetically identical cells. This process is facilitated by the close proximity and shared environment of cells within a biofilm or colony. As a result, periodontal pathogens can spread and transmit within the same colony, leading to the development of localized infections.

**Why Each Wrong Option is Incorrect**
**Option A:** Contagious refers to the ability of a pathogen to be transmitted from one individual to another. While periodontal pathogens can be transmitted between individuals, the concept of bacterial "finger printing" is more relevant to understanding the spread within colonies rather than between individuals.

**Option B:** Non-contagious is incorrect because periodontal pathogens can be transmitted between individuals, especially through close contact or shared environments.

**Option D:** Non-transmissible is incorrect because, as mentioned earlier, periodontal pathogens can spread within colonies through clonal expansion.

**Clinical Pearl / High-Yield Fact**
Bacterial "finger printing" is a useful tool for understanding the epidemiology and transmission of periodontal pathogens. It highlights the importance of considering the local environment and biofilm structure when developing treatment strategies for periodontal diseases.

**Correct Answer:**
✓ Correct Answer: C. Transmissible within members of the same colonies