#### Answer

The relation is a function.

#### Work Step by Step

The relation {(a, b), (b, c), (c, d), (d,d)} is a function. to solve this we can suppose that a=1, b=2. c=3 , d=4 and e=5.
Using these values for the variables, the set becomes {(1, 2), (2, 3), (3, 4), (4,5). This shows that the following relations is a function because for each x value there is only one y-cordinate value. Thus the relation passes the vertical line test as there are no two y values for one x values and therefore the relation is a function.