Health Cloud utilizes the Person Account object model to represent patients, which combines account and contact information into a single record. For users to have a complete view of a patient, their access rights to the underlying contact record must be synchronized with their access to the account record. The Salesforce best practice for this scenario is to set the organization-wide default (OWD) for the Contact object to 'Controlled by Parent'. This setting ensures that a user's access to the contact portion of the Person Account is inherited directly from their access to the parent account, providing seamless and unified access to the entire patient record as required.

A. Setting 'Modify All' on the Account object is an excessive permission that bypasses all sharing rules, creating a significant security risk and violating the principle of least privilege.

C. Setting the Contact object OWD to 'Private' would segregate the sharing of the contact from the account, potentially preventing users from seeing the full record even if they have access to the account.

D. Setting the Account OWD to 'Public Read Write' is overly permissive for a healthcare setting, as it would expose all patient data to all users, which is inappropriate and violates privacy standards.

1. Salesforce Health Cloud Administrator Guide, "Set Your Organization-Wide Sharing Defaults". The documentation explicitly states, "For person accounts to work properly, the organization-wide default for contacts must be set to Controlled by Parent." This is listed as a mandatory configuration step for Health Cloud.

2. Salesforce Security Guide, "Sharing Settings". In the section discussing organization-wide sharing defaults, it explains that for objects in a master-detail relationship (or special relationships like Account-Contact for Person Accounts), setting the detail object to 'Controlled by Parent' makes its sharing dependent on the master record's sharing. This is the intended mechanism for Person Accounts.

3. Trailhead, "Prepare for Your Health Cloud Implementation" module, "Set Up Your Org for Health Cloud" unit. This official training material lists the prerequisite org configurations. It instructs administrators to "From Setup, go to Sharing Settings and edit the organization-wide defaults... set Contact to Controlled by Parent." This reinforces it as a foundational implementation best practice.