The 30 rock-cut cave monuments of Maharashtra India that date back from the 2nd century BCE to the 600 CE, including paintings and sculptures considered to be masterpieces of Buddhist religious art, as well as frescos that are reminiscent of the Sigiriya paintings in Sri Lanka.

The Ajanta Caves are a series of 30 rock-cut Buddhist cave monuments located in the Aurangabad district of Maharashtra, India. These caves are renowned for their intricate paintings and sculptures, which are considered masterpieces of Buddhist religious art. The caves were carved out of solid rock between the 2nd century BCE and the 600 CE, and they are a UNESCO World Heritage site. The Ajanta Caves are particularly significant for their extensive Buddhist art and frescoes, which are reminiscent of the Sigiriya paintings in Sri Lanka.

The Ajanta Caves are divided into two groups: the first group of caves (1-12) are the chaitya-grihas (stupa halls) and viharas (monasteries) that were constructed during the Satavahana period (2nd century BCE to 2nd century CE). The second group of caves (13-29) were constructed during the Vakataka period (5th century CE) and are known for their elaborate paintings and sculptures. The paintings at Ajanta are some of the finest examples of Indian art and are known for their vibrant colors and intricate details.

The Ajanta Caves are not only significant for their artistic value but also for their historical and cultural importance. They provide valuable insights into the religious and social life of ancient India, particularly during the period of the rise and spread of Buddhism. The caves were abandoned around the 7th century CE and were rediscovered in the 19th century by a British officer who stumbled upon them while hunting.

Other rock-cut caves in Maharashtra, such as the Barabar Caves, Bhaja Caves, and Kanheri Caves, are also significant but do not match the specific criteria mentioned in the question. The Barabar Caves are located in Bihar and are older than the Ajanta Caves, dating back to the 3rd century BCE. The Bhaja Caves are located in Pune and are older than the Ajanta Caves, dating back to the 2nd century BCE. The Kanheri Caves are located in Mumbai and are not as extensive in terms of Buddhist art and frescoes as the Ajanta Caves, dating back to the 1st century BCE.

Therefore, the Ajanta Caves are the correct answer as they are the only caves that match the description of being a series of 30 rock-cut cave monuments in Maharashtra, India, known for their extensive Buddhist art and frescoes.