George and helen have an 18-year-old son, joshua, who lived with them all year and is a college student. george and helen provided all the support for joshua and all the costs of keeping up their home. joshua worked during the year and received wages of $2,000. he had $140 of federal withholding. the reeds have a balance due on their return and are unsure what to do. george, helen, and joshua are u. s. citizens with valid social security numbers. george and helen ask if their son joshua should file a tax return for 2018. how should the volunteer respond? a. joshua is exempt from filing because he is a student. b. joshua does not have to file because he is their dependent and they can claim his income on their tax return. c. joshua must file based on the 2018 filing threshold for children and other dependents. d. joshua should file a tax return to claim a refund of his withholding.