Which of the following is NOT a defining feature of mountains? Significant height above sea level
Prominence (the fact or condition of standing out from something by physically projecting or being particularly noticeable.)
Steepness
Cold weather

Lexy is correct because angle r is between the incident wave,  n  = 0, and a diffracted wave.

Answer;

hot magma rises and pushes up toward the lithosphere, and as it cools it cycles back down toward the core to be heated again.

explanation; convection currents are the circular pathways taken by a fluid that enhances heat transfer by the process known as convection which occurs in fluids.convection currents transfer heat from one place to another by mass motion of a fluid. earth mantle is in a semi-liquid state and behaves like any other fluid, rising up from the bottom of the mantle after becoming hotter and less dense from heat of the earth's core, as the rock loses heat into the earth's crust it becomes cooler and more dense, then sinking back down to the core, then repeating the cycle.