Bhimbetka is a UNESCO World Heritage Site located in the state of Madhya Pradesh in India. It is renowned for its rock shelters and cave paintings, which provide valuable insights into the prehistoric era. The paintings found at Bhimbetka span several historical periods, showcasing the artistic expressions of early human civilizations.

The correct answer is option 'A': Three.

Explaining in detail, the rock shelters at Bhimbetka contain paintings that can be categorized into three distinct periods:

1. Paleolithic Period:
The earliest paintings at Bhimbetka date back to the Paleolithic period, which is estimated to be around 30,000 years old. These paintings were created by early humans using natural pigments such as red and white ochre. The artwork primarily consists of animal figures, human figures, and geometric patterns. These paintings provide important insights into the lives and beliefs of early humans.

2. Mesolithic Period:
The Mesolithic period paintings at Bhimbetka are relatively more recent, dating back to around 10,000 years ago. These paintings depict scenes from everyday life, such as hunting, dancing, and gathering. The artwork from this period also includes various animals, birds, and mythical creatures. The colors used in these paintings are predominantly green, yellow, and white.

3. Chalcolithic Period:
The Chalcolithic period paintings at Bhimbetka are the most recent, dating back to roughly 4,000 years ago. The artwork from this period shows a transition from hunting and gathering to settled agriculture. The paintings depict agricultural activities, such as farming, harvesting, and domestication of animals. The colors used in these paintings are more varied, including shades of red, yellow, green, and white.

Overall, the rock paintings at Bhimbetka offer a unique glimpse into the artistic and cultural heritage of ancient human civilizations. They provide valuable information about the lifestyle, beliefs, and artistic capabilities of early humans. The three historical periods represented in the paintings demonstrate the progression of human civilization and the development of artistic expression over time.