It is different from specific groups or regions.
Option: b
Explanation:
The vocalization in the chimp groups is different from other groups. It's been several years; a lot of anthropologists have been researching on chimpanzees and on their vocals to find out where they came from. Chimp groups or chimpanzees produced different types of voice or vocals- alarm barks, screams, soft panting, rough grunts, pant grunts, pant barks, Waa barks, wraas, copulation screams, pant hoots and etc. So, we cannot say which group they belong to or they originated from. Therefore, the vocalization in the chimp groups is unique to specific groups or regions which are unrecognized yet.