Answer:
The first option is correct.
Step-by-step explanation:
The proportion we have is
[tex]\frac{C_1}{d_1}=\frac{C_2}{d_2}[/tex]
For the first ratio, we know that C₁ = π and d₁ = 1. This gives us the ratio
π/1.
For the second ratio, we know that d₂ = 2r and we we do not know C₂. This gives us
C₂/2r.
This gives us
[tex]\frac{\pi}{1}=\frac{C_2}{2r}[/tex]
Cross multiplying, we have
2r(π) = C₂(1)
2πr = C₂
