During the year ended December 31, 2017, Johnson City received a state grant of $600,000 to finance the purchase of buses and an additional grant of $200,000 to aid in the financing of bus operations in 2017. Both grants are expenditure-driven grants. Only $400,000 of the capital grant was expended in 2017 for the purchase of buses, but the entire operating grant of $200,000 was expended in 2017.

If Johnson City's bus transportation system is accounted for as part of an enterprise fund, how much should Johnson City report as nonoperating grant revenues for the year ended December 31, 2017?
a. $200,000
b. $400,000
c. $600,000
d. $800,000