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.

i need the answer asap !

Two conductors, a and b, are each in the shape of a tetrahedron. but of different sizes. they are charged in the following manner: 1. tetrahedron a is charged from an electrostatic generator to charge q. 2. tetrahedron a is briefly touched to tetrahedron b. 3. steps 1 and 2 are repeated until the charge on tetrahedron b reaches a maximum value. if the charge on tetrahedron b was q/4 after the first time it touched tetrahedron a. what is the final charge qbmax on tetrahedron b?