Salesforce defines strict prerequisites for converting the Individual Account model to Person Accounts because the transformation changes the underlying representation of the customer.

Each Account being converted can have only one Contact record through a single direct Account Contact Relationship. Salesforce also requires that the Account must not be the parent of any other Account. The Parent Account field must be blank, and no other Account can reference the converting Account as its parent.

Additional prerequisites include matching Account and Contact owners, matching currency values where applicable, a blank Reports To field on the Contact, and ensuring no other Contact reports to the converting Contact. These controls prevent relationship structures that cannot be represented correctly after the Account and Contact become a Person Account.

The conversion must also be thoroughly tested in a sandbox. Salesforce recommends previewing how Person Accounts affect technical architecture and customizations and instructs organizations to execute the transformation in a sandbox first because migration to Person Accounts is effectively irreversible.

Neither a blank Account Phone field nor Opportunity ownership reassignment is a documented conversion prerequisite. Therefore, the required preparations represented here are C, D, and E.