In Access the data type is called AutoNumber, in SQLServer it is called an Identity field, in Oracle is it called a

In Access the data type is called "AutoNumber," in SQLServer it is called an "Identity" field,

in Oracle is it called a "Sequence". What do they do?

Select one:

a. Automatically create candidate keys

b. Ease portability between data managers

c. Provides a field to find system information.

d. Provide a surrogate key automatically