Answer:
d.A sample of stone that is hung on a buildings walls
I believe the answer is: catgut tied to crude metal wires
The catgut is made by the intestines of mammals such as horse or sheep. Ancient Egypt was among the first one to use this method in order to preserve the teeth.
For wealthier citizens, they might use a more expensive metal for the braces. The Etruscans for example use gold as a form of brace in order to prevent tooth collapse.
The answer is personal experiences, for this term is the most important aspect if defining psychology, according to psychologist. It is because personal experience is one of the factors of having to determine things of how psychology will likely occur or what will likely trigger and help in studying it.
Answer:
One of the properties of transition elements is forming coloured compunds.