Option A is the correct answer from the supplied choices. Slack historically exposed its complete Web API method reference at `api.slack.com/methods`, and that address currently redirects to Slack's modern developer documentation under the Methods reference at `docs.slack.dev/reference/methods/`. The reference contains Slack's available method families, including `admin.*`, `apps.*`, `auth.*`, `chat.*`, `conversations.*`, `files.*`, `users.*`, `views.*`, and many others. Each individual method page identifies supported access mechanisms, OAuth scopes, parameters, response structures, errors, and rate-limit information. The pricing and legal pages are unrelated to API-method documentation, while `app.slack.com/methods` is not Slack's developer method reference. Therefore, A remains valid, although the current canonical documentation location is Slack Developer Docs.