The correct answer to your question Is C. (Semicolon). The semicolon or semi-colon is a punctuation mark that separates major sentence elements. A semicolon can be used between two closely related independent clauses, provided they are not already joined by a coordinating conjunction.
A semicolon because it acts as a space. That space is like when we take a breathe between sentences because saying it fast and not taking that space creates the words to sound funny together.