How does the comet's energy change as it moves from point A to Point D? (Assume that the total mechanical energy is conserved.)

The answer for #3 is c but i don't know why

Which statement best describes the oxidation numbers of the atoms found in magnesium chloride? a. magnesium has a 2- oxidation number and chlorine has a 1+ oxidation number. b. magnesium has a 2- oxidation number and chlorine has a 2+ oxidation number. c. magnesium has a 2+ oxidation number and chlorine has a 1- oxidation number. d. magnesium has a 1+ oxidation number and chlorine has a 1- oxidation number.

What three natural resources are found in the great lakes region