Consider the following recurrence
$$T(n)=2T(\sqrt{n})+1$$
$$T(1) = 1$$
Which of the following is true?

A

$$T(n)=O(\log \log n)$$

B

$$T(n)=O(\log n)$$

C

$$T(n)=O (\sqrt{n})$$

D

$$T(n) = O(n)$$