Which of the following is the correct way to declare a PHP class?

The correct declaration of a PHP class is done using the syntax that begins with the keyword "class," followed by the class name and a pair of curly braces that define its scope. In this case, the option which states "class MyClass {};" accurately reflects that structure. The "class" keyword is essential as it informs the PHP interpreter that a class is being defined. The curly braces are used to encapsulate the class's properties and methods, allowing for the organization of code into reusable modules.

Other options fail to adhere to the proper syntax and structure required for class declaration in PHP. For instance, "MyClass class {};" incorrectly places the class name before the "class" keyword, which does not conform to the expected syntax. Similarly, "declare MyClass class {};" introduces an unrecognized "declare" statement in this context, which is irrelevant for class declaration. Lastly, "class: MyClass {};" uses a colon instead of the required space, which is not valid in PHP syntax. Thus, option A distinctly captures the correct method of declaring a class in PHP.