In 2017, Leo's wife died. Leo has two small children, ages 2 and 4, living at home whom he supports entirely. Leo does not remarry and is not claimed as a dependent on another's return during any of this period. In 2018, 2019, and 2020, Leo's most advantageous filing status is, respectively

A.single for all three years.

B.head of household for all three years.

C.surviving spouse, surviving spouse, head of household.

D.surviving spouse, surviving spouse, single.