Which attack best demonstrates covert eavesdropping via smartphone sensors?

The Spearphone attack, covered in CEH v13 Mobile Platform Hacking, exploits smartphone accelerometers to infer speech vibrations from loudspeakers—without microphone permissions.

This attack demonstrates how built-in sensors can be abused for covert surveillance, making it ideal for assessing privacy risks.

Other options involve different attack vectors not related to sensor-based eavesdropping.

Thus, Option C is correct.