The answer above is NOT correct.
Consider the cities B, C, D, E, F, G. The costs of the possible roads between cities are given below:
c(B, C) = 14
c(B, D) = 12
c(B, F) = 11
c(C, D) = 17
c(C, F) = 15
c(C, G) = 16
c(D, E) = 19
c(D, F) = 13
c(E, G) = 18
What is the minimum cost to build a road system that connects all the cities?