Catherine earned unexpected income of $$3,000$ over the last year. Gathering up her bills, she noted that her vacation cost $$500$ less than planned and car maintenance bills were higher than expected by $$600.$ What was Catherine's budget forecasting error?

Select one:

a$.-$$$3,100$

b$.+$$$2,900$

c$.+$$$3,100$

d$.-$$$2,900$