The correctly punctuated sentence among the choices provided is:
B. The mayoral candidate will address the following issues: ideas for reducing taxes, for both individuals and businesses; proposed spending cuts, starting with his own office; and plans to fund repairs for several roads.
Colon is used to introduce a list of items following it, while semicolon is used to separate clauses which convey different ideas. In this sentence, comma is used to initiate a brief pause.