The Rocky Mountains are described as younger because the Rocky's are really two mountain chains. The older mountain chain started billions of years ago, and the younger mountain chain pushed the older mountain chain up more, only 60 millions years ago.
Crete and Euboea is the answer.
C. when did the earth form? and what is it made of?
The answer would be : D. Ocean
The earth consist of more than 70 % of water.
And from that 70 % ,
97 % of them is located on the Ocean
hope this helps