The correct answer is option 'C' - Diastema is a space in the teeth lines in mammals.

Explanation:
A diastema is a gap or space between two teeth in a dental arch. It is commonly observed in the teeth of mammals, including humans, but is particularly prominent in certain species such as rabbits.

1. Diastema in Mammals:
In mammals, the teeth are arranged in dental arcs or rows. Diastemas can occur between any two teeth in these arcs. They can be present in the upper or lower jaw and can vary in size and location depending on the species.

2. Function of Diastema:
The presence of diastemas in mammalian dental arcs serves specific functions depending on the species and their dietary habits. In some cases, diastemas allow for the proper alignment of the teeth during occlusion or closing of the jaws. This ensures that the teeth meet correctly, facilitating effective chewing and grinding of food.

3. Diastema in Rabbits:
In rabbits, diastemas are particularly significant as they play a crucial role in their unique dental anatomy and feeding behavior. Rabbits are herbivores and have evolved specialized teeth to efficiently process plant material. They possess long, continuously growing incisors at the front of their jaws, which are separated from the premolars and molars by large diastemas.

4. Effect on Chewing:
The diastemas in rabbit dentition allow for the independent movement of the incisors and the grinding teeth. This separation is essential for the proper functioning of the teeth during chewing. The incisors cut and slice through vegetation, while the premolars and molars grind and crush the food.

5. Continuous Tooth Growth:
The presence of diastemas in rabbits is also related to their continuous tooth growth. As herbivores, rabbits experience significant wear on their teeth due to the abrasive nature of their diet. The diastemas act as a buffer zone, preventing excessive wear and allowing the teeth to grow continuously to compensate for the constant grinding action.

In conclusion, diastema refers to a space in the teeth lines of mammals, including rabbits. It plays a vital role in the feeding and dental anatomy of these animals, allowing for efficient food processing and continuous tooth growth.