A study compared a sample of Swedish people older than 75 who needed in-home assistance with a similar sample of Israel people. The people in the two samples received both informal assistance, provided by family and friends, and formal assistance, professionally provided. Although Sweden and Israel have equally well-funded and comprehensive systems for providing formal assistance, the study found that the people in the Swedish sample received more formal assistance, on average, than those in the Israeli sample. Which of the following, if true, does most to explain the difference that the study? ['More Swedish than Israeli people older than 75 live in rural areas where formal assistance services are sparse or nonexistent.', 'In recent decades, the increase in life expectancy of someone who is 75 years old has been greater in Israel than in Sweden.', 'In Israel, people older than 75 tend to live with their children, whereas in Sweden people of that age tend to live alone.', 'A companion study found that among children needing special in-home care , the amount of formal assistance they received was roughly the same in Sweden as in Israel.']