You are given a math word problem and you are supposed to make use of mathematical concepts like probability, combinatorics, linear equations, sequences/series, or simple operators like addition, subtraction, division, or multiplication to answer the given question. Choose the best option from the 5 given options and report that option.

[EX Q]: Question: On an order of 5 dozen boxes of a consumer product, a retailer receives an extra dozen free. This is equivalent to allowing him a discount of:

 Option A: 15%

 Option B: 16 1/6%

 Option C: 16 2/3%

 Option D: 20%

 Option E: 30%
[EX A]: Option C

[EX Q]: Question: Today Joelle opened an interest-bearing savings account and deposited $5,000. If the annual interest rate is 5 percent compounded interest, and she neither deposits nor withdraws money for exactly 2 years, how much money will she have in the account?

 Option A: $6512.50

 Option B: $7512.50

 Option C: $5512.50

 Option D: $4512.50

 Option E: $5250.00
[EX A]: Option C

[EX Q]: Question: What is the smallest positive integer x such that 507+x is the cube of a positive integer?

 Option A: 15

 Option B: 5

 Option C: 50

 Option D: 2

 Option E: 4
[EX A]:
Option B