The correct answer is: A. HTML
HTML stands for HyperText Markup Language. It is a standard markup language for creating web pages. HTML is a text-based language that uses tags to define the structure of a web page and its content. HTML tags are enclosed in angle brackets (< >).
XML stands for Extensible Markup Language. It is a markup language that is similar to HTML, but it is more flexible and extensible. XML is used to create documents that can be stored and processed by computers.
XSD stands for XML Schema Definition. It is a language that is used to define the structure of XML documents. XSD is used to ensure that XML documents are well-formed and valid.
XSL stands for Extensible Stylesheet Language. It is a language that is used to style XML documents. XSL can be used to transform XML documents into other formats, such as HTML or PDF.
HTML is the correct answer because it is the standard file format language for web documents. HTML is used to create the structure of a web page and its content. XML, XSD, and XSL are all markup languages that can be used to create documents, but they are not used to create web pages.