which of the rivers are positioned right?
ilse, banfe, perf, allna, salzbode, bieber, dill, ulmbach, kallenbach, kerkerbach, elbbach, gelbach (aubach), emsbach
of these, which have a drainage basin area of less than 100 square kilometers? (km2)
ilse, banfe, allna, bieber, ulmbach, kallenbach, kerkerbach, emsbach
to narrow it down further, which of these has a confluence listed of less than 20? (by lahn-km)
ilse, banfe
of the remaining two, which one has a higher elevation?
ilse