Final answer:
The patient portal is the access tool used to view a subset of patient health records after logging in to a secure online website.
Step-by-step explanation:
The access tool that is used to view a subset of patient health records after logging in to a secure online website is the patient portal. A patient portal is a secure website that allows patients to access their personal health information, such as lab results, medical records, and appointment schedules. It provides a convenient way for patients to monitor their health and communicate with healthcare providers.