CAVOK applies to arriving aircraft and refers to the simultaneous occurrence at an airport of the following meteorological conditions.

• A. No cloud below 5000ft, no CBs, visibility 6NM or more, no precipitation, thunderstorms, shallow fog or low drifting snow
• B. No cloud below 5000ft, no CBs, visibility 6SM or more, no precipitation, thunderstorms, shallow fog or low drifting snow
• C. no cloud below 2500ft, visibilty 3 miles or better
• D. No cloud below 6000ft, no CBs, visibility 10KM, no precipitation

Answer: (B)

CAVOK means ceiling and visibility OK—conditions that are good enough for safe approach and landing. For arriving aircraft, this means no low cloud, no significant weather, and good visibility. The definition used here requires cloud base not lower than 5,000 ft, no CBs, visibility at least 6 statute miles, no precipitation, and no shallow fog or low drifting snow. The option that states those exact conditions matches what CAVOK describes, so it’s the best choice. The other options fail because they either allow low clouds, reduce the required visibility, or imply weather phenomena that should be absent for CAVOK (for example, allowing thunderstorm activity or cloud bases below the specified threshold).