Answer : The most likely happens during this reaction is, Oxidation-reduction
Explanation :
The balanced reaction will be,

In this reaction, neutral iron loses 3 electrons and oxidizes in (+3) state,
and neutral oxygen gains 2 electrons and reduces in (-2) state,
When iron react with oxygen gas to give iron oxide. This process is known as iron rusting. During the reaction, oxidation-reduction process occurs.
Oxidation : It is a type of chemical reaction in which a substance loses its electrons. Or we can say that in oxidation, the oxidation number increases.
Reduction : It is a type of chemical reaction in which a substance gains its electrons. Or we can say that in reduction, the oxidation number decreases.
Answer:
Hydrogen Bond
Explanation:
Hydrogen bond interactions are formed between the hydrogen atom bonded to most electronegative atoms (i.e. F, O and N) of one molecule and most electronegative atom (i.e. F, O and N) of another molecule.
In this interaction the hydrogen atom has partial positive charge and electronegative atom has partial negative charge.
M(C2H2O)= 12.0*2 +1.0*2 +16.0 = 42 g/mol is a molar mass for empirical formula.
120.6g/mol/42g/mol ≈ 3
So, empirical formula should be increased 3 times,
and molecular formula is C6H6O3.
Answer is D.