Step 1: Analyze the function of each language.
HTML (HyperText Markup Language): This is the standard markup language used to create and structure content for web pages and web applications. It is the fundamental building block of the World Wide Web.
C++: This is a high-level, general-purpose programming language used for system software, game development, and high-performance applications. It is not primarily used for creating the structure of web pages.
C Shell (csh): This is a command-line interpreter and scripting language for Unix-like operating systems.
Perl: This is a general-purpose programming language often used for web development (specifically CGI scripting in the past), but it is not the language used to structure the web pages themselves.
Step 2: Identify the correct language.
Based on the definitions, HTML is the language specifically designed for creating web pages.