For the Euclidean algorithm calculating gcd(a, b), suppose the size of the input n is defined as the length of b in its binary representation, i.e n - log2 b. What is the time complexity T(n) of the Euclidean algorithm for gcd(a, b) when a 2 bi? Assume that "mod" is a constant-time operation. O A. O(logn) O C. O(n) O D. 0(2")