The hot spots of biodiversity are characterized by:

The correct option is "high endemicity and high threat of extinction".

Biodiversity hot spots are biogeographic regions that contain significant levels of biodiversity and are under threat from human activities. To qualify as a biodiversity hot spot, a region must meet two strict criteria:
1. High Endemicity: It must contain a high concentration of endemic species—meaning species that are found native to that specific geographic area and nowhere else on Earth. Specifically, a region must contain at least 1,500 species of vascular plants as endemics (which is more than 0.5% of the world’s total).
2. High Threat of Extinction: The region must be threatened, having lost at least 70% of its original primary vegetation due to human impact and habitat destruction, placing its unique species at an extremely high risk of extinction.

Therefore, biodiversity hot spots are characterized by both high endemicity and a high threat of extinction.