Answer : 2. "नेचुरल हिस्ट्री "
Explanation :

1. Pliny the Elder was a Roman natural philosopher.

2. The book written by the Roman writer Pliny the Elder is Natural History.

3. It is an encyclopedia covering all aspects of the natural world, including geography, zoology, botany, astronomy, agriculture, mathematics, pharmacology, mining, mineralogy, sculpture, art precious stones, etc.