(a) Devaraya I                                          

(b) Mallikarjuna

(c) Vira Vijaya                                          

(d) Virupaksha

Answer: a

Explanation:

The accounts of Domingo Paes, who visited in 1520 and Fernao Nuniz, who visited in 1535, are important sources in the reconstruction of the History of Vijayanagara. Based on these accounts Robert Sewell, in 1900, wrote a book, “A Forgotten Empire: Vijayanagar”.

Nuniz states that  Devaraya I  greatly improved the city of Vijayanagara, raising fresh walls and towers, increasing its extent, and building further lines of fortification. His great work was the construction of a huge dam in the Tungabhadra River and forming an aqueduct fifteen miles long from the river into the city.

Hence, option a is correct.

Read: Previous Year UPSC History Questions (PYQs) With Explanation 2023