Which two queries are optimized for large data volumes?

Consider the following queries. For these queries, assume that there are more than 200,000 Account records. These records include soft-deleted records; that is, deleted records that are still in the Recycle Bin. Note that there are two fields that are marked as External Id on the Account. These fields are Customer_Number__c and ERP_Key__c.

Which two queries are optimized for large data volumes? Choose 2 answers
A . SELECT Id FROM Account WHERE Id IN : aListVariable
B . SELECT Id FROM Account WHERE Name != ” AND IsDeleted = false
C . SELECT Id FROM Account WHERE Name != NULL
D . SELECT Id FROM Account WHERE Name != ” AND Customer Number c = ‘ValueA’

Answer: A,D