Which one of the following in the correct sequence of German geographers contributing to the development of geographical thought ?
1
Ratzel - Troll - Hettner - Peschel
2
Peschel - Hettner - Ratzel - Troll
3
Peschel - Ratzel - Hettner - Troll
4
Troll - Hettner - Peschel - Ratzel