The correct answer is A) by combining the number of Senators and Representatives for each state.
According to the Constitution, the US directly determine the number of electoral votes received by each state by combining the number of Senators and Representatives for each state.
The process called "Electoral College" select electors to count the votes in a presidential election and the counting of the votes by the US Congress. 538 electors comprise the Electoral College. The electors by each state equal the number of members in its Congressional delegation. This means that is one for each member of the House of Representatives and two for the number of Senators each state has. To win the presidency, a candidate needs 270 electoral votes.