If scientist were to watch a planet for millions of years and see no movement on the crust it might idnicate that the planet has no a. convection below the crust b. life in its polar and subpolar regions c. atmosphere above its crust d. mountains, valleys, or meteor craters

I believe the answer is A. convection beneath the crust.  Convection beneath the crust causes the crust to shift.  This process is known as thermal convection where heat from inside of Earth causes currents of molten magma to rise towards the crust and causes cooler magma to sink and flow causing tectonic plate movement and crust movement over many years.

the correct answer is c.