3. In each case below, either draw a graph with the required properties, or prove that it doesn't exist. (a) A graph on 5 vertices with degrees 1,1,2,3,4. (b) A tree on 7 vertices with degrees 1,1,1,2,3,3,5. (c) A tree on 7 vertices with degrees 1,1,1,1,2,3,3. (d) A graph without loops or multiple edges on 5 vertices with degrees 3,3,4,4,4. (e) A graph without loops or multiple edges on 5 vertices with degrees 1,2,3,4,4.