The correct answer is Not only/ but also
Explanation:
In grammar, conjunction refers to a word or multiple words that are used to connect different element on a sentence or different sentences this includes words such as but, and, so, or, because. Additionally, conjunctions are of different types including subordinating conjunction used to link dependent clauses or clauses that do not express a complete thought and need from another sentence to be complete and coordinate conjunction that linked clauses of the same importance. Additionally, conjunctions can also be compound if they are composed by multiple words, this includes the conjunctions as well as, such as or so and other conjunctions such as either/or and not also/ but, that go together but include different elements between them. Considering this, in the sentence "Credit for the invention goes not only to Edison but also to bell" the conjunction, which is one compound conjunction is "not only/ but also".
