c. demand for that good is more elastic than if you spent a smaller portion of your income on the good.
Demand elasticity is the change in demand as the price changes - aka price has a big effect on demand.
Think about if the cost of a candy bar doubles from $1 to $2. This is a big increase but $2 isn't a huge portion of your income so it isn't a huge deal and you will probably keep buying. Now imagine if your car payment doubles from $350 to $700. Because this is such a big portion of your income, you will probably look to trade it in for a cheaper car.