Answer is D. January 1, 2014
The Patient Protection and Affordable Care Act, commonly known as Obamacare or ACA, is a health law that brought significant health care changes in America.
In March 2010, President Obama signed the Affordable Care Act into law whereas its major provisions went into effect on January 1, 2014. However, some significant changes came into effect even before this date and will continue to be followed in the years to come.