Please answer a question about the following article about Chihuahua (state):

During the Mexican Revolution, Álvaro Obregón invited a group of Canadian German-speaking Mennonites to resettle in Mexico. By the late 1920s, some 7,000 had immigrated to Chihuahua State and Durango State, almost all from Canada, only a few from the U.S. and Russia. Today, Mexico accounts for about 42% of all Mennonites in Latin America. Mennonites in the country stand out because of their light skin, hair, and eyes. They are a largely insular community that speaks a form of German and wear traditional clothing. They own their own businesses in various communities in Chihuahua, and account for about half of the state's farm economy, excelling in cheese production.

Mennonites speak a form of which language predominantly?
German