Which of the following taxpayers must file a 2015 return? 
a. Amy, age 19 and single, has $8,050 of wages, $800 of interest, and $350 of self- employment income.
b. Betty, age 67 and single, has a taxable pension of $9,100 and Social Security benefits of $6,200.
c. Chris, age 15 and single, is a dependent of his parents. Chris has earned income of $1,900 and interest of $400.
d. Dawn, age 15 and single, is a dependent of her parents. She has earned income of $400 and interest of $1,600.
e. Doug, age 25, and his wife are separated. He earned $5,000 while attending school during the year.