which of the following statements is correct regarding modified adjusted gross income on a joint return?

A) if MAGI includes $240,000 salary plus $20,000 net investment income, then $10,000 is subject to the 3.8% rate.

B) if MAGI is $260,000, including salary plus $20,000 social security benefits, all the income is subject to the 3.8% rate.

C) MAGI is the threshold amount above which all gross income is subject to the NII tax.

D) The MAGI is subject to an adjusted for inflation.