Question

How are electors to the electoral college chosen?

Answer 1

They may be State-elected officials, party leaders, or persons who have a personal or political affiliation with the Presidential candidate. On Election Day, the voters in each State choose the Electors by casting votes for the presidential candidate of their choice.

Answer 2

this is how The electors to the electoral college was chosen : they were appointed by the legislatures
Our constitution currently give the power to states legislature to determine how the electors were chosen.

Hope this helps