A car engine usually converts gasoline into motion and heat through combustion.
Oxygen acts as an aid to combustion.
Oxygen acts as an aid to a car engine converting gasoline into motion and heat.
What acts as an aid to a car engine converting gasoline into motion and heat?

(A) Energy.
(B) oxygen
(C) nitrogen
(D) helium
(E) argon
(F) energy
(G) burning
(H) sugar