**Answer: The correct option is**

**(A) ** {(14, 15), (5, 15), (3, 15), (11, 15), (5, 15)}.

**Step-by-step explanation: **We are given to select the** relation that is not a function.**

We know that

a relation in the form of ordered pairs, is not a function if **any first element is associated to more than one second elements.**

**Option (A) :** The given relation is

{(14, 15), (5, 7), (3, 10), (11, 1), (3, 8)}.

Here, we can see that the element **3 is associated to two second elements, 10 and 8.**

So, this relation is **not a function.**

**Option (A) is CORRECT.**

**Option (B) :** The given relation is

{(1, 1), (2, 2), (3, 3), (4, 4), (5, 4)}.

Here, we can see that **each first element is associated to only one second element.**

So, this relation is** a function.**

**Option (B) is NOT CORRECT.**

**Option (C) :** The given relation is

{(14, 15), (5, 7), (3, 10), (11, 1), (6,10)}.

Here, we can see that **each first element is associated to only one second element.**

**So, this relation is a function.**

**Option (C) is NOT CORRECT.**

**Option (D) :** The given relation is

{(14, 15), (5, 15), (3, 15), (11, 15), (5, 15)}.

Here, we can see that **each first element is associated to only one second element.**

**So, this relation is a function.**

**Option (D) is NOT CORRECT.**

**Thus, (A) is the correct option.**