On June 15, 2021, Louise purchased the rights to a gravel interest for $1,500,000. At that time, it was estimated that the recoverable units would be 100,000. During the year, 20,000 units were mined and 10,000 units were sold for $200,000. Louise incurred expenses during 2021 of $50,000. Louise's depletion deduction for 2021 using the percentage depletion method would be:

a. $175,000.

b. $10,000.

c. $150,000.

d. $75,000.

e. $200,000.