According to the passage, which is the principal energy source of home heat

A．gratify themselves
B．show individualism
C．keep up with the Joneses
D．boast of their wealth

A．contrast their views on the luxury consumerism in eighteenth-century England
B．indicate the inadequacy of the traditional approaches to eighteenth-century English history
C．support the contention that key questions about eighteenth-century consumerism remain unanswered
D．give examples of historians who have explored the eighteenth-century consumerism in England