Simplify the following text for a Grade 8 native English-speaking person.
Original: The most important towns in the district of Biberach are Biberach ( RiÃ ) , Riedlingen , Ochsenhausen and Laupheim .
Simplified: The major towns in the district of Biberach are Biberach an der Riss , Riedlingen , Ochsenhausen and Laupheim .