Answer:
The answer should be (b)
Step-by-step explanation:
"My brother is having a party; I have to bring several items: balloons, cake and pizza."
"My brother is having a party" and "I have to bring several items" are two independent clauses, meaning they should have a semicolon between them.
Meanwhile, "I have to bring several items: balloons, cake and pizza." is a list, which is shown by the colon.