Which class safely protects the doIt () method from concurrent thread access?

Which class safely protects the doIt () method from concurrent thread access?

A.
class SafeMethod {
Static int ID = 0;
Public static void doIt(String s) {
Synchronized (s) {
System.out.println(“Name:”+ s +”ID:”+ id++);
}
}
}

B.
class SafeMethod {
Static int ID = 0;
Public static void doIt(String s) {
Synchronized (new object () ) {
System.out.println(“Name:”+ s +”ID:”+ id++);
}
}
}

C.
class SafeMethod {
Static int ID = 0;
Public static void doIt(String s) {
Synchronized (this) {
System.out.println(“Name:”+ s +”ID:”+ id++);
}
}
}

D.
class SafeMethod {
Static int ID = 0;
Public static void doIt(String s) {
Synchronized (SafeMethod.class) {
System.out.println(“Name:”+ s +”ID:”+ id++);
}
}
}

Explanation:
It should be pointed out that:

public void blah() {
synchronized (this) {
// do stuff
}
}
is semantically equivalent to:

public synchronized void blah() {
// do stuff
}

Incorrect answer:
B: A constructor cannot be synchronized.