Sam is married and files a joint return with his spouse, Lana. Both Sam and Lana are 67 years old. Their combined gross income was $30,000. What is their taxable income? Are they required to file a tax return?

A. A. Their taxable income is $0. They are not required to file a return.

B. B. Their taxable income is $2200. They are required to file a return.

C. B. Their taxable income is $4,900. They are required to file a return.

D. D. Their taxable income is $28,300. They are required to file a return.