Question 3.26

26. Which of the following statements is true?

  1. The vertices of a graph that can be drawn in the plane so that the edges meet only at the vertices can always be colored with at most three colors.
  2. The number of inequivalent (non-isomorphic) graphs that can be vertex-colored with exactly three colors is finite.
  3. The vertices of a graph that can be drawn in the plane so that the edges meet only at the vertices can be colored with at most four colors.

26.

c