Given the following classes and their objects:

```
class C1 {};
class C2 extends C1 {};
class C3 extends C1 {};

C2 c2 = new C2();
C3 c3 = new C3();
```
Analyze the following statement:
c2 = (C2)((C1)c3);
a. c3 is cast into c2 successfully.
b. You will get a runtime error because you cannot cast objects from sibling classes.
c. You will get a runtime error because the Java runtime system cannot perform multiple casting in nested form.
d. The statement is correct.

b. You will get a runtime error because you cannot cast objects from sibling classes.