In PHP source code embedded in HTML, what is the purpose of the special PHP opening and closing tags such as <?php and ?>?

Introduction / Context:
PHP was designed as a server side scripting language that can be mixed directly into HTML pages. To support this style, PHP uses special tags that signal when script blocks start and end. This question checks your understanding of what those tags do and why they are necessary in mixed PHP and HTML files.

Given Data / Assumptions:

• PHP files often contain both HTML markup and PHP code.
• The server must know which segments to parse and execute as PHP instructions.
• The common tags are to end it.

Concept / Approach:
When the web server passes a file to the PHP engine, the engine scans through the content. Any text that appears outside PHP tags is treated as literal output and is sent directly to the browser. Any text that appears inside PHP tags is parsed and executed as PHP code. The most portable and recommended tags are to close. There are also short tags in some configurations, but these can be disabled and are less portable across environments.

Step-by-Step Solution:
Step 1: Consider a simple file where HTML and PHP are mixed.Step 2: The PHP engine needs a clear signal to know where script execution should start.Step 3: The tag is found.Step 4: Text outside these tags is not executed and becomes part of the HTTP response as plain HTML.Step 5: Therefore, the main purpose of these tags is to mark PHP code blocks, which is exactly what option A describes.

Verification / Alternative check:
If you remove the opening tag from a PHP block, the server will output the code itself instead of executing it, or it may treat the file as plain text. If you forget the closing tag, PHP will attempt to parse everything that follows as PHP, which can lead to parse errors. This practical behaviour reinforces that the tags are markers for executable PHP sections, not encryption or commenting features.

Why Other Options Are Wrong:
Option B claims that the tags encrypt code, which they do not; they simply mark code segments. Option C suggests the tags are used only for comments, but PHP comments use //, /* */, or #. Option D incorrectly associates the tags with class scope, which is unrelated to embedding PHP in HTML.

Common Pitfalls:
One pitfall is relying on short tags like

Final Answer:
They mark the beginning and end of PHP code blocks inside a file so that the PHP engine knows which parts to execute as PHP and which parts to treat as plain HTML.