What key capability must primary flight instrumentation provide regarding unusual attitudes?

Primary flight instrumentation must provide unusual attitude recovery capability to ensure that pilots can respond effectively when an aircraft experiences abnormal flight conditions. This capability is critical because unusual attitudes, which can occur due to various reasons such as pilot error, turbulence, or system malfunctions, can lead to loss of control if not addressed promptly and correctly.

Instruments designed for this purpose typically offer pilots clear and instantaneous feedback about the airplane's orientation, such as pitch and roll information. This information enables pilots to identify when an aircraft is outside of its normal operational attitude and assists in executing the necessary recovery procedures. By providing precise data on the aircraft's attitude, primary flight instruments can help mitigate the risks associated with unusual flight situations and enhance overall flight safety.

While other options might offer valuable information or assistance, they do not directly address the urgent need for pilots to recognize and recover from unusual attitudes in flight, which can be life-threatening if not managed effectively.