(Click the Picture for my question) and thank you!

Answer:
D
Step-by-step explanation:
By definition, π is defined to be the ratio of a circle's circumference to its diameter. In other words:
[tex]\displaystyle \pi=\frac{C}{d}[/tex]
In fact, if you multiply both sides by the diameter d, you can see that:
[tex]C=\pi d[/tex]
Which is the formula for circumference you've been commonly taught.