it could be like x^3 where it has a horizontal point of inflection
or it could be in the form of the more general cubic which has x^2 and x terms. here it would have 2 turning points since the power is three.
if u want it to have only one x intercept all the tp has to be above the x axis like so :
View attachment 38810
so then its local max an min have the same signs. on this image they are both positive.
if u shift the curve down so the xint is on the right part they are both negative.
Wait but the thing is i forgot what a local max or min is. im pretty sure they refer to turning points? cuz global max and min are the ends i think. so then it should be D