What of the following can be the best title for the passage

A．We should shop as Mary did.
B．Readers have to be careful when buying products.
C．Goods made by hand are sure to be better than those made on assembly lines.
D．It is better for Mary to buy a new toaster.

A．Fire and metals are both very important.
B．The science of preparing metal for use began before the use of fire.
C．Tools, weapon and decorations can only be made from metals.
D．Fire has been playing an very important part in their life and work since human beings mastered its use.