Which two changes should a developer make in this trigger to adhere to best practices?

Consider the above trigger intended to assign the Account to the manager of the Account”s region .

Which two changes should a developer make in this trigger to adhere to best practices? Choose 2 answers
A . Use a Map accountMap instead of List accountList.
B . Use a Map to cache the results of the Region__c query by Id.
C . Move the Region__c query to outside the loop.
D . Remove the last line updating accountList as it is not needed.

Answer: C,D