Melochord (its a musical instrument)
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Samaddar-er Chabi
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Bakho Rohossho
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Naepolean-er Chithi
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Bhushorgo Bhoyonkor
A
Correct answer
Explanation
The question mentions 'Melochord' described as a musical instrument. 'Samaddar-er Chabi' (Samaddar's Key) is a Feluda novel where a key is the central object. If the Melochord is related to a musical element or key in the story, this would be the correct answer. The other options don't specifically feature musical instruments as central plot elements.