An algorithm runs a given input size n.If n is 4096,the run time is 512 ms .If n is 16384 the run time is 2048 ms .what is the complexity of the algorithm in big-o notaion ?

a)o(n^1/2)

b)o(n)

c)o(nlogn)

d)o(n^2)

o() is big-oh!

is it logical ? I have seen this on some website. can we guess the answer or this is some non-sense ? please explain. thanks.