The function that generates the sequence 1, 2, 4, 8, ... is:
Of(x) = 2^(x-1)
We can check this by plugging in the first few values of x:
Of(1) = 2^(1-1) = 1
Of(2) = 2^(2-1) = 2
Of(3) = 2^(3-1) = 4
Of(4) = 2^(4-1) = 8
Therefore, the answer is option B.