Given А and В tables that both contain <i>row</i>

Given А and В tables that both contain row column. Table А contains 10 records while table В contains 5 records. How many records will the following query return?

SELECT A.row, B.row FROM A, B

Explanation

SELECT ... FROM table_1, table_2

query uses cross join to link two tables (since there is no WHERE clause).
It returns a Cartesian Product of records from both tables - a result set containing table_1 * table_2 records.