The correct answer is A. Slack enablement should be experiential, especially for core user behaviors such as replying in threads and reacting with emoji. These are not concepts users master by seeing a screenshot or answering a quiz; they need to perform the actions inside Slack. Setting aside live practice time allows participants to reply in a thread, react to a message, observe how threads keep the main channel clean, and understand how emoji reactions can replace low-value follow-up messages. Option B is passive and does not prove the learner can perform the task. Option C checks memory, not skill. Option D can support post-session reinforcement, but it does not ensure attendees can perform the activities after training. A strong Slack learning session should combine demonstration with guided practice in a training channel. This gives learners confidence and makes adoption more realistic because they practice the exact behavior they will use in daily collaboration.