Iron Metal Reacts with Oxygen Gas to Produce Iron(III) Oxide

Iron metal reacts with oxygen gas to produce iron(III) oxide. What will be the effect of increasing concentration of oxygen gas in a closed reaction vessel?

A) There is no effect; a catalyst is needed.
B) The rate of production of iron oxide will slow down.
C) More iron oxide will be produced.
D) The reaction mixture will catch fire.
E) Less reaction will take place.