Determine whether each of the following taxpayers must file a return in 2018:

a. Jamie is a dependent who has wages of $4,150.

b. Joel is a dependent who has interest income of $1,200.

c. Martin is self-employed. His gross business receipts are $24,050, and business expenses are $24,300. His only other income is $2,600 in dividends from stock he owns.

d. Valerie is 68 and unmarried. Her income consists of $6,500 in Social Security benefits and $15,000 from a qualified employer-provided pension plan.

e. Raul and Yvonne are married and have 2 dependent children. Their only income is Raul's $26,000 salary.