Which of the following is most likely to happen when a plate carrying oceanic crust collides with a plate carrying continental crust?
a. the denser oceanic plate gradually sinks into the mantle and melts.
b. the less dense continental plate gradually sinks into the mantle and melts.
c. both the oceanic and the continental plates sink into the mantle and melt.
d. the plates collide and mantle convection stops.

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Amichelson interferometer operating at a 600 nm wavelength has a 3.02-cm-long glass cell in one arm. to begin, the air is pumped out of the cell and mirror m2 is adjusted to produce a bright spot at the center of the interference pattern. then a valve is opened and air is slowly admitted into the cell. the index of refraction of air at 1.00 atm pressure is 1.00028.how many bright-dark-bright fringe shifts are observed as the cell fills with air?