Answer:
Option c
or 
Step-by-step explanation:
The absolute value is a function that transforms any value x into a positive number.
Therefore, for the function
x> 0 for all real numbers.
Then the inequation:
has two cases
if
(i)
if
(ii)
We solve the case (i)

We solve the case (ii)

Then the solution is:
or 
Given that the concentration has been modeled by the formula:
C(t)=50t/(t^2+25)
where:
t is time in hours.
The concentration after 5 hours will be given by:
t= 5 hours
plugging the value in the equation we get:
C(5)=(50(5))/(5^2+25)
simplifying the above we get:
C(5)=250/(50)=5 mg/dl
Answer: 5 mg/dl
Are you trying to figure out what X is? One of the equations equal to 4, and the rest equal to 24.