The dog is 4 years old.
For Greg's prediction:
![y=(1)/(2)x](https://img.qammunity.org/2023/formulas/mathematics/high-school/nabzjkdehz167djomj2imkro9b16cn2vpr.png)
Where x represents the age.
Set x=4, then:
![\begin{gathered} y=(1)/(2)x \\ y=(1)/(2)(4) \\ y=2 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/iv1h6wrgbmk80etpt7skbcubg8wayvoe5z.png)
So, Greg predicts 2 pounds.
Now, looking at the graph.
When x=4 the line is 7.
Hence, the graph predicts 7 pounds. So, Greg's prediction is incorrect.
The correct answer is option C.