What would be the outcome of this command?

Sales details are being stored on a daily basis in the SALES_2007 table. A large amount of
data is added to the table daily. To save disk space, you issued the following command:
ALTER TABLE sales_2007 COMPRESS FOR ALL OPERATIONS;
What would be the outcome of this command?

A.
It produces an error because data already exists in the table.

B.
It produces an error because compression can be enabled at table creation only.

C.
It compresses all data added or modified henceforth but the existing data in the table is
not compressed immediately.

D.
It immediately compresses all existing data as well as new data, resulting from either
fresh additions or modifications to existing data.