The anti-tampering technology of Huawei WAF products is based on the cache module. Suppose that when user A visits website B, website B has page tampering.

Signs: The workflow for the WAF tamper-proof module has the following steps:.

① WAF uses the pages in the cache to return to the client;

②WAF compares the watermark of the server page content with the page content in the cache

③Store the content of the page in the cache after learning

④ When the user accesses the Web page, the WAF obtains the page content of the server

⑤WAF starts the learning mode to learn the page content of the user's visit to the website;

For the ordering of these steps, which of the following options is correct?