Consider a transportation problem with two source nodes $1, $2, and n demand nodes 1, ..., n. All ares (si, j) are assumed to be present and to have infinite capacity. Let D = 2 d; be the total demand. Let the supply at each source node be equal to D/2. Assume that di > 0 for all i. (a) (4 points) How many basic variables are there in a basic feasible solution? (b) (6 points) Show that there exists a degenerate basic feasible solution if and only if there exists some set S C {1, ...,n} such that isd; = D/2