What is the relationship among these three terms: independent variable, dependent variable, and constant?

Which mantle is under the crust the upper mantle or the lower mantle i think it's upper let me know if i'm right

What noticeable trend from this graph might be used to make a conclusion?

The diagram below shows the layers of a rock having a trilobite: a rock column labeled rock is shown. the column has three layers. the bottommost layer of the rock has one shaded rhomboid shape, the middle layer has a rhombus with a diagonal along with two identical organisms marked as, trilobite, in the key, the top layer has two semicircles. a key is shown on the right side of the diagram. the shaded rhombus is marked as a, the rhombus with the diagonal is marked as b, the semicircle is marked as c which statement about the rock fossils is true?