Which of the following classic Tour de France mountains is the lowest?

Explanation

The real mountains first became part of Tour de France. Then director Henri Desgrange decided to make the route a bit more exciting by adding mountains. Since then, mountains have always made up part of the Tour. Some of the 'regulars' are Col du Galibier (2645 m), Col du Tourmalet (2115 m), Col du Madelin (1993 m), Mont Ventoux (1912 m), L'Alpe d'Huez (1860 m) and Hautacam (1560 m).