In Drupal's official documentation, headless Drupal is described as decoupled Drupal . The documentation explains that decoupled, or headless, Drupal separates the backend content management part of Drupal from the frontend presentation layer . In this architecture, Drupal is used as a content repository and content API, while the frontend can be built with other technologies such as JavaScript frameworks or consumed by other clients. This directly supports option C Drupal documentation also explains that this architecture allows Drupal content to be exposed to other systems and applications through APIs such as JSON:API or REST. That means Drupal can provide content to websites, mobile apps, kiosks, or other digital channels, which matches option B . The purpose of headless Drupal is therefore not automatic updates or automatic publishing, so options A and D are not correct.
So, according to Drupal 10 and Drupal 11 documentation, the correct understanding is that headless Drupal means decoupled Drupal and involves exposing Drupal-managed content to external systems or applications through APIs .