Final answer:
The extension of a simple web page is .html, which stands for HyperText Markup Language and is the standard file format for creating the structure and content of web pages.
Step-by-step explanation:
The extension of a simple web page is .html. When we talk about a simple web page, the most basic file type that defines its structure and content is an HTML (HyperText Markup Language) file, which uses the .html extension. This is the standard markup language used for creating web pages and web applications. While other extensions like .css, .js, and .php are also commonly used in web development, they serve different purposes:
- .css files are Cascading Style Sheets and are used for styling the appearance of web pages.
- .js files are JavaScript files and are used for adding interactivity to web pages.
- .php files are PHP (Hypertext Preprocessor) scripts and are used for server-side scripting and generating dynamic page content.
Therefore, the correct answer to the question is A) .html.