Final answer:
A record of immunizations belongs to the history section (a) of a health history, documenting the patient's past vaccinations and showcasing their immune protection status.
Step-by-step explanation:
In a health history, a record of immunizations belongs to the history section (a). The history section of a patient’s health records is a comprehensive account of their medical background, which includes past illnesses, surgeries, and importantly, vaccinations received. The other sections, such as current illness (b), review of systems (c), and physical assessment (d), serve different purposes. Specifically, the immunizations information is critical as it shows the immune protection the patient might have and can impact the clinical management of their current health concerns, highlighting the tie between immunological memory and the efficacy of vaccinations.