Which of the following is an example of objective data?

Objective data refers to information that can be observed and measured, as opposed to subjective data, which is based on personal experiences, feelings, or opinions. The blood pressure reading of 120/80 is a prime example of objective data because it is a measurable, quantifiable figure obtained through clinical assessment. This kind of data is not influenced by the patient's perceptions or emotions; it is a factual measurement that can be verified by another clinician or through additional tests.

In contrast, the other options represent subjective data, as they rely on the patient's personal accounts and interpretations of their symptoms or medical history. For instance, when a patient reports a headache or describes feeling anxious, these statements reflect their personal experience and cannot be directly measured. Similarly, stating an allergy to penicillin is based on the patient’s subjective history rather than an observable or measurable clinical finding.