Question 1.7

7. The valences of the vertices in the accompanying graph, listed in decreasing order, are

image
  1. 6, 4, 3, 3, 3, 2, 1, 1, 1.
  2. 1, 3, 4, 4, 5, 5.
  3. 5, 5, 4, 3, 3, 1, 1, 1.

7.

a