abstract class A {

public int do_stuff1() {

return 3;

}

public abstract int do_stuff2() {};

public void do_stuff3() {

return;

}

public abstract int do_stuff4();

}

Given the following code, which method will cause a compile error: abstract class A{ public int do_stuff1() \{ return 3; \} public abstract int do_stuff2() \{\}; public void do_stuff3() \{ return; ] public abstract int do_stuff4(); ] do_stuff10 do_stuff2() do_stuff3() do_stuff4() More than one method will cause a compile error