which of the following transactions adds to u.s. gdp for 2015? a. in 2015, ann sells a car that she bought in 2011 to bill for $7,000. b. an american management consultant works in canada during the summer of 2015 and earns the equivalent of $40,000 during that time. c. when ken and kim were both single, they lived in separate apartments and each paid $800 in rent. ken and kim got married in 2015 and they bought a previously unoccupied house that, according to reliable estimates, could be rented for $1,700 per month. d. none of the above transactions adds to u.s. gdp for 2015.