C is the answer. By only looking at the domain (the stuff on the right in the functions), you can see that the first equation has a hole at x=2, meaning it does not have a value here at x=2. When x<2, there are values for the 1st function. When x>2, there are values for the second function, as well as when x=2
^ means to the power of or exponent
logb(x) = y is b^y = x
Given, Shelby made 5 quarts of juice for a picnic.
We know that 1 quart of juice = 4 cups of juice.
Here we will have to convert 5 quarts to cups.
As for 1 quart there are 4 cups, to find 5 quarts we have to multiply 4 times 5.
So 5 quarts of juice =
cups of juice.
We know that, 
5 quarts of juice = 20 cups of juice.
We have got the required answer here.
Shelby made 20 cups of juice there in the picnic.