Detailed Solution:
The correct answer is “Chandragupta Maurya”.
Chandragupta Maurya was the first ruler to take the initiative for water resource management in the Girnar region by instructing his brother-in-law and Viceroy, Pushyagupta, to build the Sudarsana Lake.
The Junagadh rock inscription of Rudradaman I, a Western Satraps ruler, states that Pushyagupta was in charge of building a dam on the Sudarshana Lake near Girnar in Kathiawar, shortly after 150 CE.