Answer:
A. 
Step-by-step explanation:
The options are:

For this exercise it is important to remember that, by definition, the Exponential parent functions have the form shown below:

Where "a" is the base.
There are several transformations for a function f(x), some of those transformations are shown below:
1. If
and
, then the function is stretched vertically by a factor of "b".
2. If
and
, then the function is compressed vertically by a factor of "b"
Therefore, based on the information given above, you can identify that the function that represents a vertical stretch of an Exponential function, is the one given in the Option A. This is:

Where the factor is:

And 
f(x)= -2 (x - 2) ( x - 4)
if x=2 ⇒ f(x)=y=0 ⇒ graph of f(x) intercept x axis in (2,0)
if x=4 ⇒ f(x)=y=0 ⇒ graph of f(x) intercept x axis in (4,0)
if x=0 ⇒f(x)= -2 *(-2)*(-4)= - 16 ⇒ graph of f(x) intercept y axis in (0,- 16)
⇒ f(x)= -2 (x - 2) ( x - 4) is the answer
Answer: 10
Step-by-step explanation:(-x)(5y)(-2x)
=(-5xy)(-2x)
=10x^2y
therefore,the coefficient of the equation is 10.