In figures without numbers or distance labels, don’t make assumptions about relative distances. In this figure, you can trust that *a* < *b* < *c* < *d*, but you cannot assume anything about *how much* greater *b* is than *a* or *how much* greater *c* is than *b*, etc. The text indicates that *c* = –*a*, which means those points have opposite signs. Since *a* < *c*, it must be that *a* is negative and *c* is positive (this would also imply that *d* is positive). Thus, zero is between *a* and *c*, and equidistant from both. Don’t assume that *b* is negative because it might appear to be closer to *a* than to *c*; zero might be on either side of *b*, since the figure is not necessarily drawn to scale.

So, *a* is definitely negative, *c* and *d* are definitely positive, but *b* could be either positive or negative.

(A) *abd* = (negative)(positive or negative)(positive) = negative or positive

(B) *acd* = (negative)(positive)(positive) = negative

(C) *b*^{2}*d* = (positive or negative)^{2}(positive) = (positive)(positive) = positive

(D) *bcd* = (positive or negative)(positive)(positive) = positive or negative

(E) *cd*^{2} = (positive)(positive)^{2} = positive

The correct answer is B.