The following question is based on information obtained from the Wildi textbook, Chapter 16. 

Large synchronous generators have to be responsive to changes in current demand from the infinite bus. In order to maintain a stable voltage and minimize fluctuations in the alternators terminal output, utilities will use what type of exciter that will monitor voltage conditions and send control signals to increase or lower the excitation current feeding the alternator and automatically adjust the output voltage due to changing conditions.

Please select the most correct answer from the selection provided below.