a$.$ Amy, age $19$ and single, has $$8,050$ of wages, $$800$ of interest, and $$350$ of self$-$employment income.

A$.$ Amy must file even though her gross income is less than the threshold of $$14,600$ because her self$-$employment income is greater than $$200.$

B$.$ Amy must file because her gross income exceeds the threshold of $$5,050.$

C$.$ Amy need not file because her gross income is less than the threshold of $$14,600$ and her self$-$employment income is less than $$1,300.$

D$.$ Amy need not file because her gross income is less than the threshold of $$14,600$ and her self$-$employment income is less than $$400.$