Answer:
B. 7 3/8 inches (
 inches)
Explanation:
 So we have 3 
 to start. 
 is added every day, so the number of days can be x. Our equation will look like this:
y = 3 
 + 
x
where y is how tall the pile is and x is the number of days.
 They give us a x value, which is 5, as it says "after 5 days" so we can plug that into our equation:
y = 3 
 + 
x
y = 3 
 + 
(5)
Now, let's solve.
 Multiply the 5 into the three fourths:
y = 3 
 + 

 Now we need to add them together, I am going to turn 3 
 into an improper fraction:
3 * 8 = 24
24 + 5 = 29
29 / 8
 Next, let's turn 15/4 into a common denominator of 29/8 by multiplying both the numberator and the denominator by 2:
30/8
 Then, let's add:
y = 

 Last, I am going to turn it into a mixed number so we can chose our answer.

 This brings us to our answer of B.