The correct answer is Option 1) i.e. extremely poorIn the sentence given above, we have two independent clauses which are joint by coordinating conjunction 'but'. The word 'but' is one of the seven coordinating conjunctions in English (the others are and, or, so, for, nor, and yet). Its used to connect two statements that contrast or contradict each other in some way. Now the first part of the sentence is positive in nature so the second part must contradict this, so the only contradicting option we have is 'extremely poor'.Let's see some examples in order to develop more clarity:learning Mathematics is difficult but fun!She is the smartest girl in the class but I don't like her.Complete Sentence: His knowledge of the subject was excellent but his classroom performance was extremely poor.