Answer:
It's y = (5)(0.2)^x
_____________
Explanation:
Exponential functions have a standard form of ab^x
Where a is the starting value, and b is the exponential growth or decay.
Because the numbers are getting smaller and smaller, it is a decay so b must be less than one.
We can eliminate the first choice because when x is 1, y is 1. If this where the equation we would get (5) (1/2) ^ 1 = 5 × 1/2 = 2.5 ≠ 1.
So the answer must be the second choice.