Solution
= Solution
Assume every category of elements of a representable presheaf is a preorder. Let
$$
P=\coprod_{A\in\operatorname{ob}\mathcal C}(1\downarrow\mathcal C(-,A)).
$$
A disjoint union of preorders is a preorder. The category-of-elements projection $P\to\mathcal C$ is a <discrete fibration>. It is surjective on objects because $B\in\mathcal C$ is the image of the object $1_B:B\to B$ in the summand indexed by $B$.