To answer this question we need to find out the nth term
(aka the position-term rule) of this sequence. You'll notice that every term is the previous one multiplied by 2 - it's doubling each time. So we can say that the rule is 2ⁿ, where n is the position of the term in the sequence. Using the laws of exponents, 2ⁿ is equal to 2(2)ⁿ⁻¹. So the answer from the four options is 2(2)ⁿ⁻¹.
Hope this helps!
