What three things should the architect consider to optimize performance of the data migration?

The architect is planning a large data migration for Universal Containers from their legacy CRM system to Salesforce.

What three things should the architect consider to optimize performance of the data migration? Choose 3 answers
A . Review the time zones of the User loading the data.
B . Remove custom indexes on the data being loaded.
C . Determine if the legacy system is still in use.
D . Defer sharing calculations of the Salesforce Org.
E . Deactivate approval processes and workflow rules.

Answer: B,D,E