The correct answer is A. They are appointed by the state legislatures.
Step-by-step explanation:
The Electoral College includes 538 representatives from all the states of the U.S. whose responsibility is to choose a President and a Vice President every four years as part of the Presidential Elections. This means the electoral college aims at representing all citizens in the U.S. Besides, the election of members of the electoral college is in charge of the legislature of each state. Due to this, there is not a general method for choosing electors but each state legislature appoints the electors based on different methods or criteria. Thus, option A is correct.