Write SQL query to solve given problem: Among the low income countries, which country has the lowest fertility rate?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT T2.CountryName FROM Country AS T1 INNER JOIN Indicators AS T2 ON T1.CountryCode = T2.CountryCode WHERE T1.IncomeGroup = 'Low income' AND T2.IndicatorName = 'Adolescent fertility rate (births per 1,000 women ages 15-19)' ORDER BY T2.Value LIMIT 1