Final answer:
The beta sugar configuration is necessary as a base for attachment of other sugars to produce ABO antigens.
Step-by-step explanation:
The sugar configuration necessary as a base for attachment of other sugars to produce ABO antigens is the beta configuration. In the context of ABO blood type antigens, if the -OH group on the anomeric carbon atom is towards the left, it is known as the beta (B) anomer or ß-sugar. This anomer is the base for the attachment of other sugars, such as N-acetyl galactosamine in type A blood or galactose in type B blood, to form the specific ABO antigens that determine an individual's blood type.