A single remote piezoelectric sensor unit should NOT be used to cover multiple rooms because _____.

The correct reasoning behind why a single remote piezoelectric sensor unit should not be used to cover multiple rooms is that high frequencies typically do not travel well around corners. Piezoelectric sensors are designed to detect vibrations and can be sensitive to specific frequency ranges. When sound waves, which include high frequencies generated by human activities, encounter obstacles such as walls, they tend to dissipate and lose energy, making it difficult for the sensor to detect them effectively in adjacent rooms.

In scenarios where coverage across multiple rooms is required, the inability of these high frequencies to bend or effectively propagate around corners would lead to gaps in detection. This means that activities or sounds in one room might not be detected by a sensor positioned in another room due to this limitation, ultimately reducing the effectiveness of security monitoring.

While other factors such as power requirements, connectivity, and range could be considerations for different types of sensors, the primary issue with using a single piezoelectric sensor across multiple rooms is its inability to effectively detect high-frequency sounds in an environment with obstacles.