Add a new column to an existing table

Which of the following statements is the correct syntax for adding a new column called Gender into a table called dbo.Contact that already contains data?

A. ALTER TABLE dbo.Contact ADD COLUMN Gender CHAR(1) NOT NULL
B. ALTER TABLE dbo.Contact ADD COLUMN Gender CHAR(1) NULL
C. ALTER TABLE dbo.Contact ADD Gender CHAR(1) NOT NULL
D. ALTER TABLE dbo.Contact ADD Gender CHAR(1) NULL

Answer:[D]
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