In this Oct. 6, 2015, file photo, the HealthCare.gov website, where people can buy health insurance, is displayed on a laptop screen in Washington. About 9 in 10 Americans now have health insurance, more than at any time in history. But progress is incomplete, and the future far from certain. Rising costs could bedevil the next occupant of the White House. Millions of people previously shut out have been covered by President Barack Obama's health care law. No one can be denied coverage anymore because of a pre-existing condition. But "Obamacare" remains divisive, and premiums for next year are rising sharply in many communities. How does source B corroborate the information in source A? a It confirms that citizens under a certain age can continue to use their parents' plan b It discusses the high monetary cost of the Affordable Care Act c It shows that insurance companies are leaving the insurance exchanges d It describes a drop in the uninsured rate across the country