Answer: B) semicolon.
Step-by-step explanation: when we have a compound sentence (a sentence that has at least two independent clauses) we have two ways to separate the clauses, using a comma or a semicolon. The comma is used when we have a coordinating conjunction (like and, but, yet, nor, or, etc), and the semicolon is used usually when we have to separate two clauses that are closely related with each other, in this case, the independent clauses are "Soon Yi is hoping to earn a music scholarship" and "she practices piano everyday", the second one is the consequence of the first one, so we separate them with a semicolon: "Soon Yi is hoping to earn a music scholarship; she practices piano everyday".