Which of the following might the President do in the case of violent riots in a major American city?

Explanation:

b- is the only answer thats makes sense.

a curfew would be imposed by the mayor or gov., laws are already in place making rioting illegal, and there is no reason to negotiate a treaty with a state's gov.  

the answer is: must pay taxes on profits

since it is considered as a part of your income, profits from investments is eligible for tax payment.

the tax from your investment could be influenced by how long you decided to sell it. united states promotes keeping your investment for long term period. so, the tax rate for investments that you sell in less than one year is typically higher compared to investments that you sell in more than one year period.