Match each front with its description. when a warm air mass slides over a cold air
mass
cold front
when a cold air mass and a warm air mass
meet and do not move
occluded front
when a cold air mass slides under a warm
air mass
warm front
when two cold fronts force a warm front up
and block it from the surface
stationary front

i'm thinking (a) to keep sand in place; ////////////

explanation: a sand fence or sandbreak, like a snow fence, is used to force windblown, drifting sand to accumulate in a desired place. sand fences are employed to control erosion, sand dune stabilization, keep sand off roadways, and to recruit new material in desert areas.

that is true   : ) hope this you

the tricuspid valve is present between right atrium and right ventricle