In ionic bonding, atoms SHARE ELECTRONS
One mole of Fe(NO3)3, or iron(III) nitrate, has three moles of nitrate molecules, which have three moles of oxygen atoms each. We can show this mathematically:
1 mole Fe(NO3)3 * (3 moles NO3)/(1 mole Fe(NO3)3) = 3 moles NO3
3 moles NO3 * (3 moles Oxygen)/(1 mole NO3) = 9 moles Oxygen
9 moles of Oxygen in one mole Fe(NO3)3
The fumaric acid reacts with water and forms fumarate anion and the hydronium ion which has acidic behavior. The reaction is reversible one due to the weakly hydrolysis of fumaric acid.
The answer is D=Making new fossil fuels, hope this helps:)