Question: Which of the following set of ordered pair is a function?
A $\{(9,0), (9, 1), (9,2), (9,3)\}$
B $\{(-1,0), (-2, 0), (2,0), (1,0)\}$
C $\{(-2,0), (3, 1), (3,2), (1,3)\}$
D $\{(9,5), (9, 5), (9,5), (9,5)\}$
1. **State the problem:** We need to determine which of the given sets of ordered pairs represents a function.
2. **Recall the definition of a function:** A set of ordered pairs is a function if every input (first element of each pair) corresponds to exactly one output (second element).
3. **Analyze each set:**
- Set A: $\{(9,0), (9,1), (9,2), (9,3)\}$
- The input $9$ maps to multiple outputs $0, 1, 2, 3$.
- This violates the function rule.
- Set B: $\{(-1,0), (-2,0), (2,0), (1,0)\}$
- Inputs are $-1, -2, 2, 1$ each mapping to output $0$.
- Each input has exactly one output.
- This is a function.
- Set C: $\{(-2,0), (3,1), (3,2), (1,3)\}$
- Input $3$ maps to outputs $1$ and $2$.
- Violates the function rule.
- Set D: $\{(9,5), (9,5), (9,5), (9,5)\}$
- Input $9$ maps to output $5$ consistently.
- This is a function.
4. **Conclusion:** Sets B and D are functions.
**Final answer:** Sets B and D represent functions.