A person has paid $50,000 into a fixed annuity over 20 years. When he decides to begin income payments, the insurer calculates that he will receive $4,000 per year for life, which means that he will receive a total of $100,000. In the first 10 years of payments, how much is taxable each year?

a) $4,000
b) $2,000
c) $5,000
d) $10,000