what is wrong with this question?
when plates collide, the denser plate will ride over the less-dense plate.
2 answers
That isn't a question
The statement is reversed. The more dense plate will be forced under the less dense plate. This is discussed in thre site below. Scroll down about half way on the page.
http://regentsprep.org/Regents/earthsci/units/earthquakes/tectonics.cfm
http://regentsprep.org/Regents/earthsci/units/earthquakes/tectonics.cfm