Answer:
The answer is: letter a. Require the electors to be chosen by state legislature.
Explanation:
"Electoral College" consists of electors who have been chosen under the United States Constitution. Every state has the right to have some electors who cast votes during the election of the president and the vice-president. They are selected by "state legislatures," which means their selection will depend on the "State laws." They are also selected according to some processes (particularly, two processes). The total number of electors is 538.
Under the Constitution, a person, who currently holds an office of trust or an office of profit, will not be chosen as an electorate. Every State will need to provide the elector's certification in order to qualify.