Sedimentary rocks are changed to metamorphic rocks due to subduction and temperature.
Explanation:
Metamorphic rocks are made up of other existing rocks like Igneous rocks and Sedimentary rocks.
When the existing rocks are subjected to enough pressure and temperature, they undergo permanent deformation and are turned into metamorphic rocks.
The pressure exerted on the already existing rocks is mainly due to the subduction activity of the plates. The formation of metamorphic rocks mainly occurs below the Earth's surface.