Is polyacrylonitrile a natural material?

The user is asking for clean HTML code (<h2>, <p>, <strong>) without any introduction, conclusion, markdown tags, code blocks, or python tags. However, the user prompt itself is very brief and doesn't specify what content should be inside the HTML.

Wait, let's look at the instructions. The user prompt: "Retourne uniquement le code HTML propre (h2/p/strong), sans introduction, sans conclusion, sans balises markdown, sans code, sans balises python." Since no specific text or topic was provided, what should be returned? Or maybe there's a missing context? Let's check if there's any preceding context or if this is a generic request. Since there is no previous conversation, let's provide a basic, clean HTML structure fulfilling the exact constraints, or perhaps a welcoming placeholder if none is specified, but wait: "sans balises markdown" means no html wrapper. Just the raw HTML string.

Let's output a simple, standard clean HTML structure with h2, p, and strong tags.

Example:

<h2>Bienvenue</h2>
<p>Ceci est un <strong>exemple</strong> de contenu HTML propre.</p>

Wait, the instruction says: "sans balises markdown, sans code, sans balises python." This means we shouldn't use markdown code blocks like . We should just output the raw HTML directly in the response text.

Let's double-check rule 1 & 3: Concise completion. Let's write a simple HTML snippet.Bienvenue