Variable Shadowing with an Instance Variable

Consider the following ShadowError class. When the main method is executed, the program prints 0. Which of the following statements best explains this behavior?

public class ShadowError {
    int counter = 0;
    
    public void increase() {
        for (int i = 0; i < 5; i++) {
            int counter = 0;
            counter += i;
        }
        System.out.println(counter);
    }
    
    public static void main(String[] args) {
        ShadowError s = new ShadowError();
        s.increase();
    }
}