Final answer:
Option A is grammatically correct because it forms a complete sentence without unnecessary commas, maintaining the flow and meaning of the sentence.
Step-by-step explanation:
The statement in question is about the grammatical correctness of a sentence featuring a salamander and a mushroom microphone. Option A, 'A salamander sings opera into a mushroom microphone.' is the correct statement as it is grammatically correct and does not contain unnecessary commas that could disrupt the flow of the sentence. The subject of this sentence is 'a salamander' and the verb is 'sings.' The remainder of the sentence ('opera into a mushroom microphone') serves as the predicate that tells what the subject does. No commas are required because there are no subordinate clauses or additional phrases that need to be separated from the main clause.