Here is the solution to the problem: i) a) The voltage level of the digital output signal from the Arduino UNO is either 5 V (HIGH) or 0 V (LOW). b) The type of control system implemented in the setup is an open-loop control system. Reason: The output (the alarm/buzzer) does not provide any feedback to the input (PIR sensor) or the controller (Arduino) to modify its action. The system simply responds to the input without any self-correction or adjustment based on the output. c) An interfacing device that can be used to safely control the 220 V AC alarm is a relay. ii) Here is an Arduino program to control the system: `cpp // Define the digital pins for the PIR sensor and the buzzer const int pirSensorPin = 2; // PIR sensor connected to digital pin 2 const int buzzerPin = 3; // Buzzer connected to digital pin 3 void setup() { // Initialize the PIR sensor pin as an INPUT pinMode(pirSensorPin, INPUT); // Initialize the buzzer pin as an OUTPUT pinMode(buzzerPin, OUTPUT); // Optional: Start serial communication for debugging // Serial.begin(9600); // Serial.println("Intruder Alert System Initialized"); } void loop() { // Read the state of the PIR sensor // pirState will be HIGH (1) if motion is detected, LOW (0) otherwise int pirState = digitalRead(pirSensorPin); // Check if motion is detected if (pirState == HIGH) { // If motion is detected, turn the buzzer ON digitalWrite(buzzerPin, HIGH); // Optional: Print status to serial monitor // Serial.println("Motion Detected! Buzzer ON."); } else { // If no motion is detected, turn the buzzer OFF digitalWrite(buzzerPin, LOW); // Optional: Print status to serial monitor // Serial.println("No Motion. Buzzer OFF."); } // A small delay can be added to prevent rapid toggling or to debounce the sensor // delay(50); } `