Ans: Option (C) Correlative Conjunction.
"not only... but also" is a correlative conjunction. Correlative conjunctions are used to connect two equal grammatical items. In your question, the two grammatical items that are connected by the correlative conjunction, not only... but also, are the noun phrases. One noun phrase is "a great player", and the other noun phrase is "an exceptional coach." Other examples of Correlative Conjunctions are either... or, neither... nor etc.
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