a$.$ Angela, age $19$ and single, has $$7,600$ of wages, $$650$ of interest, and $$290$ of self$-$employment income.

A$.$ Angela need not file because her gross income is less than the threshold of $$13,850$ and her self$-$employment income is less than $$400.$

B$.$ Angela need not file because her gross income is less than the threshold of $$13,850$ and her self$-$employment income is less than $$1,250.$

C$.$ Angela must file because her gross income exceeds the threshold of $$4,700.$

D$.$ Angela must file even though her gross income is less than the threshold of $$13,850$ because her self$-$employment income is greater than $$200.$

b$.$ Bria, age $67$ and single, has a taxable pension of $$8,850$ and Social Security benefits of $$5,900($the Social Security benefits are wholly tax$-$exempt in this situation$).$

A$.$ Bria must file, as her gross income exceeds the limit of $$1,850.$

B$.$ Bria need not file, as her gross income is less than $$27,700.$

C$.$ Bria need not file, as her gross income is less than $$13,850.$

D$.$ Bria need not file, as her gross income is less than $$15,700.$

c$.$ Connor, age $15$ and single, is a dependent of his parents. Connor has wages of $$2,300$ and interest of $$575.$

A$.$ Connor need not file because his gross income of $$2,875$ is less than the standard deduction of $$13,850.$

B$.$ Connor must file, as his gross income of $$2,875$ exceeds his standard deduction of $$1,250.$

C$.$ Connor must file, as his gross income of $$2,875$ exceeds his standard deduction of $$2,700.$

D$.$ Connor need not file because his gross income of $$2,875$ is less than the threshold of $$4,700.$

d$.$ Denise, age $15$ and single, is a dependent of her parents. She has wages of $$700$ and interest of $$1,300.$

A$.$ Denise must file because her unearned income is over $$1,250$ and her total gross income exceeds her standard deduction.

B$.$ Denise must file because her unearned income is over $$1,250,$ even though her total gross income is less than the threshold of $$4,700.$

C$.$ Denise must file because her unearned income is over $$1,250,$ even though her total gross income is less than the standard deduction of $$13,850.$

D$.$ Denise need not file because her total gross income is less than the threshold of $$13,850.$

e$.$ Declan, age $25,$ and his wife are separated. He earned $$5,400$ while attending school during the year.

A$.$ Declan need not file because his gross income is less than the threshold of $$13,850.$

B$.$ Declan need not file because his gross income is less than the standard deduction of $$27,700.$

C$.$ Declan must file because his gross income is over $$5$ and he is married and not living with his spouse.

D$.$ Declan must file because his gross income is over $$1,250$ and he is married and not living with his spouse.