Anna works in sales and earns $100 each week plus $15 per sale. This week, she wants to be paid at least $500. Which inequality can be used to find the number of sales she needs to make?
A. 100-15x ≤ 500
B. 100+15x ≤ 500
C. 100-15x ≥500
D. 100+15x ≥ 500