The SQL NATURAL JOIN is a type of EQUI JOIN and is structured in such a way that, columns with the same name of associated tables will appear once only.
In equi join we need to explicitly put the "=" operator
This is an example of natural join:
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SELECT *
FROM table1
NATURAL JOIN table2;
Example of Equi join(All natural joins are equijoins by definition):
SELECT column_list
FROM table1, table2....
WHERE table1.column_name =
table2.column_name;
Hence in the above question both the answers are correct A and C.