Which statement correctly describes how disabled UI controls should appear and behave?

• A. Reduced opacity and non-interactive.
• B. Disabled elements appear normal but don't respond.
• C. Disabled elements highlight with glow.
• D. Disabled elements increase size.

Answer: (A)

When a control is not available, it should clearly signal that it cannot be used. The best way is to fade it visually (reduced opacity) and make it non-interactive. This combination instantly communicates to users that the control exists but is currently unavailable, helping prevent attempts to press it or focus it.

The visual fade is a universal cue: it lowers the element’s prominence without removing its context, so users understand why it’s not usable. At the same time, it should be actually non-interactive (not respond to clicks and, for keyboard users, typically not be in the tab order). For assistive tech, the control should expose a disabled state (via a disabled attribute for form controls or aria-disabled for other controls) so screen readers convey that it’s unavailable.

Options that keep the control looking normal, or that add a glow or enlarge it, imply that the control is interactive and invite action, which contradicts its disabled status.