What is not allowed if a specific runway arrival/departure wind information is unavailable due to sensor issues?

Providing alternative wind information is the correct answer in this scenario. When specific runway arrival or departure wind information is unavailable due to sensor issues, it is critical for air traffic control to maintain safety and operational efficiency. Providing alternative wind information sourced from other reliable means, such as nearby weather stations, is essential for pilots to make informed decisions about takeoffs and landings. This ensures that the aircraft can operate safely, adhering to minimum wind limits for the specific runways in use.

In the context of the other options, delaying all flights or landing all aircraft immediately could lead to substantial operational disruptions and may not be necessary if reliable alternative wind information is available. Approving takeoffs and landings without caution would be highly irresponsible and dangerous, as it could lead to significant safety risks in cases of adverse wind conditions. Hence, providing alternative wind information represents a proactive and responsible approach when sensor information is not currently accessible.