What factor can cause a false high blood pressure reading?

A tightly fitted blood pressure cuff can indeed lead to a false high reading. When the cuff is applied too snugly, it can compress the arteries more than necessary. This excessive pressure can cause the blood flow to be impeded, resulting in higher systolic readings. For accurate blood pressure measurements, it is essential to use a properly sized cuff and ensure that it is neither too tight nor too loose, allowing for correct detection of the blood flow sounds during the measurement process.

The other options describe scenarios that are generally favorable for obtaining accurate blood pressure readings. Being seated quietly for 10 minutes helps to stabilize the blood pressure, measuring on a bare arm minimizes variables related to clothing, and allowing the patient's arm to rest at the appropriate height ensures effective circulation and reduces variability in measurements.