The correct answer is (b). The Natural History is a work by Pliny the Elder, not Ptolemy.
Pliny the Elder was a Roman author, naturalist, and philosopher. He is best known for his work Naturalis Historia, which is an encyclopedia of the natural world. The work is divided into 37 books and covers a wide range of topics, including geography, botany, zoology, mineralogy, and medicine.
Ptolemy was a Greek astronomer, geographer, and mathematician. He is best known for his work Almagest, which is a treatise on astronomy. The work is divided into 13 books and covers a wide range of topics, including the motion of the planets, the size and shape of the Earth, and the construction of astronomical instruments.
The Historial is a work by Pompeius Trogus Philippical. The work is a history of the world from the Trojan War to the death of Alexander the Great. The work is divided into 44 books, but only the first 14 books survive.
The Histories is a work by Herodotus. The work is a history of the Greco-Persian Wars. The work is divided into nine books and covers the period from the accession of Cyrus the Great to the death of Xerxes I.