If ()f(x) is a continuous function on [,][a,b] with a unique critical point which occurs at a point (,)c(a,b), and if ()f(x) does not change sign as x moves across c, then the global maximum of ()f(x) on [,][a,b]...

a. must occur at =x=a or =x=b, but not both.

b.

could occur at =x=a, =x=b, or both.

c.

does not exist on [,][a,b]

d.

must occur at =x=c.