David Invested $20,000 in the Stock Market

David invested $20,000 in the stock market. None of his stocks paid dividends, but after one year, his portfolio was worth $30,000. The relevant capital gains tax rate was 15%. What was
David's after-tax return on this investment, assuming he liquidated his portfolio?

A) 27.5%
B) 42.5%
C) 22.8%
D) 127.5%