Question

Which letter is the correct answer and why

Answer 1

Answer:

Option C

Step-by-step explanation:

Here,

[Taking 'A' = 'a']

$a \: = \: 4\pi {r}^{2}$

Then for 'r',

$= > 4\pi {r}^{2} = a$

$= > {r}^{2} = \frac{a}{4\pi}$

$= > r = \sqrt{\frac{a}{4\pi} }$

$= > r = \frac{1}{2}\sqrt{ \frac{a}{\pi} }$

Hence,

Option C is correct .