You are building an app and want to follow Slack design guidelines closely.

A and C are the two choices that best align with the current official Slack design guidance. Slack emphasizes concise, easily processed content. Applications should communicate clearly and minimize unnecessary cognitive load so users can understand information quickly rather than reading lengthy or overly complex interfaces. This supports the principle represented by option A. Slack's Block Kit design guidance also recommends simplifying suitable information with pictures. For example, faces may communicate user identity more efficiently than lists of names, and maps can sometimes communicate location more effectively than text. Images must still be accessible through appropriate alt_text; the recommendation is not to remove essential textual meaning indiscriminately. Option B is incorrect under current official guidance. Slack explicitly states that shortcut names should start with a verb, not a noun. Option D conflicts with Slack's recommendation to avoid excessive notifications, while option E is directly contrary to the guidance to reduce complexity by progressively revealing controls and information. The supplied document marks A and B, but B conflicts with Slack's published developer guidance and therefore should not be retained as the verified answer. This question belongs under Design a Great User Experience.