An external provider wants to get a patient's allergy information from Bloomington Caregivers' Health Cloud...

Step-by-Step Explanation:

Requirement:

External provider needs access to patient allergy information.

Interoperability API:

Salesforce Health Cloud provides FHIR-based Interoperability APIs that expose clinical data, including AllergyIntolerance resources.

“Use the Health Cloud Interoperability API (FHIR R4) to retrieve AllergyIntolerance resources and other clinical data for a patient.”— Health Cloud Interoperability API Guide

Other Options:

Clinical Summary Healthcare API: Provides a summary but not structured, granular allergy data.

AllergyMedication API: Not a standard Salesforce API.

Patient Healthcare API: Broader resource, but allergies specifically are available through the Interoperability API.