Enthuware

The second option:

It improves security and maintainability

This sounds pretty vague to me. How does the module system improve security and maintainability?

Not really. It is quite simple. Modularization prevents access to classes that are not intended to be accessed by others. This protection is provided by the JVM. This makes it more secure because there are less chances of exploiting any weakness.
Modularization also prevents unintented dependency on classes/packages of a library. This obviously makes an application more maintainable.

For more detailed discussion, you may go through this book or this book.