Analysis of test questions: Engel coefficient refers to the proportion of food expenditure to total household expenditure. The increase of Engel's coefficient means that the proportion of food expenditure in total household expenditure increases. Engel's coefficient is an important index to measure the living standard of residents. If Engel's coefficient is too large, it will inevitably affect other consumption expenditures and limit the improvement of consumption level and quality. The decline of Engel coefficient usually indicates the improvement of people's living standards and consumption structure. Therefore, this question chooses item C.
Comments: This question chooses the wrong A, and thinks that the decrease of Engel coefficient means that the food consumption expenditure of urban and rural residents is decreasing continuously. The reason is that I don't understand the meaning of Engel coefficient. This question is moderately difficult.