Answer:
A) $450
Explanation:
The current Medicare tax for high-income taxpayers is 2.35% for employees and 3.8% for self-employed during 2019.
Since Christine and Doug are married, they must pay the regular 1.45% + 0.9% additional Medicare care for any income above $250,000.
So the additional Medicare tax = ($300,000 - $250,000) x 0.9% = $450
*Their total Medicare tax for 2019 = ($250,000 x 1.45%) + ($50,000 x 2.35%) = $4,800