Must cast their state's formal votes for president.

Presidential electors

Presidential Electors must cast their formal votes to elect President.

Explanation: As we know that USA is comprised of 50 states. Each with their own governing bodies. Because the head of the state is single thus, all states are given equal right to vote for the president election. So, presidential electors is a body of electors chosen in different states and whose sole duty is to vote for president and vice president of United states of America.

in mcculloch v. maryland (1819) the supreme court ruled that congress had implied powers under the necessary and proper clause of article i, section 8 of the constitution to create the second bank of the united states and that the state of maryland lacked the power to tax the bank.

gibbons v. ogden, (1824), was a landmark decision in which the supreme court of the united states held that the power to regulate interstate commerce, granted to congress by the commerce clause of the united states constitution, encompassed the power to regulate navigation.

number 4. should be the correct answer