Given:
[tex]d_1=1,d_2=2r[/tex]
The circumference of the circle is given as,
[tex]C=2\pi r[/tex]
For the circle B, the circumference is given as,
[tex]\begin{gathered} C_B=\pi\cdot d_2_{}=2\pi r \\ It\text{ can also be written as,} \\ \frac{1}{2r}=\frac{\pi}{C_B} \end{gathered}[/tex]
Answer: option a)
