单选题：Questions are based on the following passage．We are locked i

Questions are based on the following passage．
We are locked in a generational war. No one wants to admit this, because it's uglyand unwelcome. Parents are supposed to care for their children, and children are supposedto care for their aging parents. For families, these collective obligations may work. Butwhat makes sense for families doesn't always succeed for society as a whole. The clash ofgenerations is intensifying.
Last week, a federal judge ruled that Detroit qualifies for municipal bankruptcy.This almost certainly means that pensions and health benefits for the city's retired workerswill be trimmed. There's a basic conflict between paying for all retirement benefits andsupporting adequate current services. The number of Detroit's retired workers has swelled,benefits were not adequately funded and the city's economy isn't strong enough to takecare of both without self-defeating tax increases.
The math is unforgiving. Detroit now has two retirees for every active worker,reports the Detroit Free Press; in 2012, that was 10,525 employees and 21,113 retirees.
Satisfying retirees inevitably shortchanges their children and grandchildren. ThoughDetroit's situation is extreme, it's not unique. Pension benefits were once thought to belegally and politically impregnable (不受影响的 ) . Pension cuts in Illinois, RhodeIsland and elsewhere have shattered this assumption. Chicago is considering reductionsfor its retirees.
What's occurring at the state and local levels is an incomplete and imperfect effortto balance the interests of young and old. Conflicts vary depending on benefits' generosityand the strength---or weakness---of local economies. A study of 173 cities by the Centerfor Retirement Research at Boston College found pension costs averaged 7.9 percent oftax revenues, but those of many cities were much higher. Health benefits add to costs.
At the federal level, even this sloppy generational reckoning is missing. Theelderly's interests are running roughshod ( 冷酷无情的) over other national concems.
Social Security, Medicare and Medicaid--programs heavily for the retired--dominate thebudget, accounting for about 44 percent of spending, and have been largely excluded fromdeficit-reduction measures.
Almost all the adjustment falls on other programs: defense, courts, research, roads,education. Or higher taxes. The federal government is increasingly a transfer agency:
Taxes from the young and middle-aged are spent on the elderly.
The explanation for this is politics. For states and localities, benefit cuts affectgovernment workers, while at the federal level, it's all the elderly, a huge group thatincludes everyone's parents and grandparents. As a result, the combat has beenlopsided (不平衡的 ) . Younger Americans have generally been clueless about howshifting demographics threaten their future government services and taxes.
What does the word "'assumption" refer to in Paragraph 3? A．Pensions are legal and won't be affected by politics.
B．Pensions are easily affected by government policies.
C．Pensions are largely paid by the elderly.
D．Pensions are largely paid by tax.