State tax filing

1. Your 1099-DIV box 12 has federal obligations that are automatically state exempt. Your  1099-INT box 3 is the same. You are not making a choice for box 12. You have  box 1 dividends, that contain your state and municipal obligations. Option 2 would limit the SC amounts so the other amounts are taxable in SC.

SC begins with the federal return. It has an addback for state and local obligations outside of SC that were exempt on the federal. (The federal does not tax state obligations). SC does not have any requirements for holding percentages like some other states. 

2. You do want to enter multiple states for the rest of the income (from other state and local obligations) along with your SC income.

Note: I can't see your 1099-B to know if box 1 contains other items pertinent to this answer. Carefully review your 1099-B.