Which of the following is  not  a principle of relative-age dating?                 a.  rock-forming materials are deposited in horizontal layers, though they may be tilted later.      b.  sediments are deposited in lateral sheets, but their orders often change.      c.  if one rock contains pieces of another, the rock containing the pieces is older than the pieces.      d.  in undisturbed rock layers, the youngest rocks are on the bottom.

The correct option is D.
In geology, relative age dating refers to the science of determining the relative order of past events in rock formation without necessarily determining the absolute age of the rocks. The five principles that are used in relative age dating are: original horizontality, superposition, lateral continuity, crosscutting relationship and inclusions.
The principle of superposition states that, when rocks are undistributed, oldest rocks will be at the bottom and the youngest rocks will be at the top.

8.7 degrees celsius and 15.6 degrees fahrenheit

Hydrogen is the most abundant element on the periodic table..hope it .