Correct option is (c) Activates the ADC Circuit to read voltage values
Easiest explanation: The Arduino has an onboard ADC (Analog to Digital Convertor) Circuit which when invoked by the analogRead() function, takes the voltage from the pin that is specified by the program and compares them with the threshold value (5V on the Arduino UNO, 7V on the Arduino Mini and Nano, etc.) and then provides a value ranging from 0 to 1023.