Final answer:
An increase in consumer incomes and a decrease in the price of heating oil can cause an increase in the demand for natural gas as a heating option.
Step-by-step explanation:
Factors that can cause an increase in the demand for natural gas include an increase in consumer incomes and a decrease in the price of heating oil. For example, if consumer incomes increase, homeowners may be more willing and able to purchase natural gas as a heating option. Additionally, if the price of heating oil decreases, some homeowners may switch to natural gas as a more affordable alternative.