(A) One example of a Hamiltonian path is D, E, A, C, B because following this path "visits" each vertex exactly once.

(B) A Hamiltonian circuit is just a Hamiltonian path that ends adjacent to where it began. A, E, B, C, D, is one such path. The cost will be 700+600+900+400 = 2600.

(C) A, C, D, B, E is another Hamiltonian circuit. The cost is 200+400+300+600 = 1500.