What is the maximum IRA contribution that Mr. Janson can make under each of the following assumptions? a. He is age 20 and single. His only income item is $13,500 interest from a trust fund. b. He is age 40 and single. His only income item is a $34,600 share of ordinary income from a partnership. c. He is age 60 and single. His only income item is $22,900 wages from his job. d. He is age 46 and files a joint return with his wife. His sole proprietorship generates a $7,770 loss, and his wife's salary is $44,300. a. Maximum contribution b. Maximum contribution c. Maximum contribution d. Maximum contribution