The diagrams below are supposed to represent level sets
for a function with isolated critical points. The heights of the
levels are shown by the numbers around the edges.
Some of the diagrams are incorrect, however. Indicate the ones that
are correct by marking them "T" and the ones that are
in error by marking them "F". (If a level's height is
not marked, the diagram is considered correct if there exists a number
that would work for that level.)
In order to get credit for this problem all answers must be correct.