Fill in the blank with correct word. Priya and Radha are the_____of friends.

Answer: best — the sentence becomes "Priya and Radha are the best of friends."

Why this is correct: The construction 'the ___ of friends' requires the superlative form of the adjective. 'Best' is the superlative of 'good', so it fits this pattern.

Notes and alternatives:

• Great: As given, 'great' is the positive form. You can say 'Priya and Radha are great friends' (no 'the' and 'of'). To use the given pattern you would need the superlative: 'Priya and Radha are the greatest of friends.'

• Good: 'Good' is the positive form. 'Priya and Radha are good friends' is correct without 'the' and 'of'. For the blank in the sentence, the superlative 'best' is required: 'Priya and Radha are the best of friends.'

• Close: 'Close' is the positive form. You can say 'Priya and Radha are close friends', or use the superlative to match the pattern: 'Priya and Radha are the closest of friends.'

Summary: Use the superlative form when the sentence uses 'the ___ of friends'; therefore 'best' is the correct choice here.