Write SQL query to solve given problem: Which region has the lowest number of countries?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT T.r_name FROM ( SELECT T1.r_name, COUNT(T2.n_name) AS num FROM region AS T1 INNER JOIN nation AS T2 ON T1.r_regionkey = T2.n_regionkey GROUP BY T1.r_name ) AS T ORDER BY T.num LIMIT 1