Could someone please explain this question for me?

The profitP(in millions of dollars) for a recreational vehicle is modeled by a quadratic function of the form

P= at2+ bt+ c, wheretrepresents the year.

a)ais positive and-b/(2a)<t

b)ais positive andt<-b/(2a)

c)ais negative and-b/(2a)<t

d)ais negative and t<-b/(2a)