The central idea of the excerpt is:
d) demonstrates the importance of consumer spending for the overall economy.
The excerpt develops this idea by highlighting that American households increased their spending, contributing to gross domestic product (GDP) growth. It notes that consumer spending accounts for nearly 70 percent of the economy and points out factors like an improving job market and lower fuel prices that are likely to sustain this spending. The text also emphasizes that consumer spending will be crucial in supporting economic expansion amidst challenges such as global demand fluctuations and external economic pressures. Thus, the excerpt underscores how vital consumer spending is for the overall health and expansion of the economy.