What was Mohorovičić's observation?(1 point) Responses Seismic waves penetrated all Earth's layers. Seismic waves penetrated all Earth's layers. Seismic waves travelled at varying speeds. Seismic waves travelled at varying speeds. Seismic waves could not go through the brittle crust. Seismic waves could not go through the brittle crust. Seismic waves travelled at constant speeds.

Mohorovičić's observation was that seismic waves could not go through the brittle crust.