Answer: D. as a total number of family member increases the amount of money that the family spends on food increases
Step-by-step explanation:
i.e. independent variable acts like a cause to effect the dependent variable.
This can be seen only in Option D. as it is very obvious that increase in family member will increase the cost of food.
Hence, there is direct effect of number of people on food's cost.
Rest of options represents correlation but not causation .
Hence, the correction option is D.