What is the first step Lenoxsoft should take to allow Salesforce to become the primary recordholder?

Prior to starting implementation, LenoxSoft wishes to consolidate all their data within Salesforce. They currently use three different systems, including Salesforce, to manage their customer data. All data does NOT currently reside in one system, and Lenoxsoft wants Salesforce to be the primary system for customer records.

What is the first step Lenoxsoft should take to allow Salesforce to become the primary recordholder?
A . Add custom prospect fields to Marketing Cloud Account Engagement and map to Salesforce.
B . Import and merge existing records from all systems to Marketing Cloud Account Engagement
C . Import and merge existing records from all systems to Salesforce
D . Add custom account fields to Marketing Cloud Account Engagement and map to Salesforce

Answer: C