In chemistry a metal is an element that readily forms positive ions and has metallic bonds. A metal is a material that when freshly prepared, polished or fractured, shows a lustrous appearance and conducts electricity and heat relatively well. Metals are typically malleable or ductile. The table shows the reaction of different metals with water.

Metal    Reaction with water   Reaction with steam
P             None                                     Mild
Q              Mild                                  Vigorous
R          Very slow                             Vigorous
S             Vigorous                             Violent


Which metal is indicated by R?
(a) Mg
(b) Al
(c) Fe
(d) Cu