100% = 1600
120% = 1920
1920/120 = 1536/y
1920y = <span>184320 (cross multiply)
y = 96%
decrease of 24% from 1920</span>
Answer: Choice D 
Reason:
Exponential functions have the variable in the exponent.
Choice A is a polynomial, which means we can rule it out. Choice B is a log function, so we can rule it out also.
Choice C is a rational function because it is a ratio of two polynomials. This rules out choice C.
Choice D is the only function with the variable in the exponent. That is assuming you meant to say
instead of 
Given:
The equation is:

Find-:
Binomials factor of the equation
Explanation-:
The quadratic equation,

Solve for factor

Then the factor is:

So, the factor is x + 4