Which of the following is considered a subjective data indicator of cardiac arrest?

The correct choice is chest pain, as it is considered a subjective data indicator of cardiac arrest. Subjective data refers to information that is based on personal feelings, interpretations, or opinions rather than observable facts. In this context, chest pain is often reported by the patient and represents their personal experience of discomfort or pain, which may lead to the concern of a cardiac event or arrest.

In contrast, unresponsiveness, rapid shallow breathing, and pulselessness are all classified as objective indicators. These signs can be observed and measured by medical personnel or bystanders; they do not rely on a patient's self-reporting. Unresponsiveness indicates a lack of reaction to stimuli, rapid shallow breathing reflects the respiratory status, and pulselessness directly signifies the absence of a detectable pulse, all of which can be verified through direct observation or medical assessment.