Answer:
Option C
Explanation:
We have : $\frac{\sqrt{25}+\sqrt{100}+\sqrt{25}+\sqrt{100}}{5}=6$ ;
$\frac{\sqrt{25}+\sqrt{81}+\sqrt{36}+\sqrt{25}}{5}=5$
$\frac{\sqrt{25}+\sqrt{25}+\sqrt{25}+\sqrt{25}}{5}=4$
So missing number is $\frac{\sqrt{49}+\sqrt{36}+\sqrt{16}+\sqrt{9}}{5}=4$