How can the constructor be identified in a class file?

How can the constructor be identified in a class file?

1. The name of the constructor is the same as the name of the class.
2. The name of the constructor is the same as the name of the file.
3. The constructor is like a method, but it has no return type.

 I only

 II only

 III only

 I and III only

 I, II, and III