The correct answer is: b) Distinctive culture.
Particularly Vulnerable Tribal Groups (PVTGs) are tribal communities that are particularly vulnerable to exploitation and marginalization. They are characterized by their distinctive culture, which often includes their own language, religion, and customs. PVTGs are often found in remote areas and have limited access to education, healthcare, and other basic services.
Option a) is incorrect because PVTGs are not necessarily large populations. In fact, many PVTGs are very small in number.
Option c) is incorrect because PVTGs do not necessarily have a pre-agricultural economy. Many PVTGs have adopted agriculture, but they may also practice other traditional livelihoods such as hunting, gathering, and fishing.
Option d) is incorrect because PVTGs do not necessarily have high literacy rates. In fact, many PVTGs have low literacy rates due to limited access to education.