None of those describe this function.
It's not a constant function, because it is not equal to a constant (something that isn't a variable)
It doesn't show direct variation, because it can't be represented in the form
y = kx.
It isn't an absolute value function because the absolute value isn't taken anywhere.
If it was an absolute value function it would look something like this:

It isn't a greatest integer function, because the greatest integer isn't taken anywhere.
If it was a greatest integer function it would look something like this:

Are you sure you typed that question right?
Answer:
I believe it's B.Let me know if it's right,if it not,i'm so sorry
Step-by-step explanation:
4x+3(2x-1) -4x 3(2x-1)= 6x-3 -4x 4x+6x-4x= 6x-3
So.. in this case, the starting amount is the 500mg sample... and the rate of decay, negative rate, is 1%, and at the time, the elapsed days is 0, to t = 0, P = 400