Determine if S is a junction.

1. s = {(1, 2), (2, 3), (4, 5), (1, 3))

2. s = {(3, 7), (1, 7), (3, 9), (6, 7), (10, 0))

3. S = {(a, 2), (b, 3), (c, 3), (d, 3), (e, 2)}

4. S = {(a, 2), (a, 3), (b, 5), (b, 7)}

5. Sis given by the table.

6. Sis given by the table.