One of the main benefits of using OOP in PHP is that it helps in organizing the code in a ______ and modular way.

The main benefit of using OOP in PHP is that it helps in organizing the code in a clear and structured way. Object-oriented programming allows for modular development, where code is encapsulated within classes and objects. The correct option is "Clear and structured." While hierarchical, linear, and flexible can be desirable qualities, they don't specifically capture the main benefit of organization and modularity provided by OOP. For more information, consult the PHP documentation on object-oriented programming: http://php.net/manual/en/language.oop5.php