Explanation:

- Cost of rice: 3 kg of rice costs ?180. Therefore, 1 kg of rice costs ?60.

- Cost of pulses in rice terms: Since 8 kg of rice (8 x ?60 = ?480) is equal to 5 kg of pulses, 1 kg of pulse costs ?96.

- Cost of tea in pulse terms: 15 kg of pulses costs 15 x ?96 = ?1440, which is equal to 2 kg of tea. Therefore, 1 kg of tea costs ?720.

- Cost of walnuts in tea terms: 3 kg of tea (3 x ?720 = ?2160) is equal to 6 kg of walnuts. Therefore, 1 kg of walnuts costs ?360.

- Cost of 10 kg of walnuts: 10 kg of walnuts costs 10 x ?360 = ?3600.

Option 4 (?3600) is correct.

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