Step 1: Place the site on the map.
Nagarjunakonda is in Andhra Pradesh, close to the Telangana border.
Step 2: Link it with the dam.
The site is on a hill island inside the lake of Nagarjuna Sagar. A lake of that size is formed by damming a large river.
Step 3: Name the river.
Nagarjuna Sagar is a dam on the Krishna river. So the island and its amphitheatre lie in the midst of the Krishna.
Step 4: Rule out the others.
Godavari, Mahanadi and Ganga flow in other parts of India and have no dam by that name here.
Step 5: Conclude.
The answer is option (1), Krishna.
Final Answer:
Option (1), Krishna, is correct.
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