Christine and Doug are married. In 2018, Christine earns a salary of $250,000 and Doug earns a salary of $50,000. They have no other income and work for the same employers for all of 2018. How much 0.9 percent Medicare tax for high-income taxpayers will Christine and Doug have to pay with their 2018 income tax return? 

a. $450 

b. $900 

c. $2,700 

d. None