Given: public class MarkList { int num; public static void graceMarks(MarkList obj4) { obj4.num += 10; } public static void main (String[] args) { MarkList obj1 = new MarkList(); MarkList obj2 = obj1;

Only one `new MarkList()` statement is executed in the `main` method, which creates a single object in memory. The subsequent assignments like `obj2 = obj1` and `obj3 = null` only create new reference variables or assign an existing reference, but do not instantiate additional objects.

This is incorrect because `obj2 = obj1` makes `obj2` refer to the same object as `obj1`, it does not create a new object instance.

This is incorrect because `obj3 = null` assigns a null reference to `obj3` and does not create an object.

This is incorrect as only one object is instantiated with the `new` keyword, regardless of how many reference variables point to it or are set to null.