The profit P (in millions of dollars) for a recreational vehicle is modeled by a quadratic function of the form
P = at2 + bt + c, where t represents the year
a) a is positive and -b/(2a) < t
b) a is positive and t < -b/(2a)
c) a is negative and -b/(2a) < t
d) a is negative and t < -b/(2a)