Suppose George made $20,000 last year and that he lives in the country of Harmony. The way Harmony levies income taxes, each citizen must pay 10% in taxes on their first $10,000 in earnings and then 50% in taxes on anything else they might earn. So given that George earned $20,000 last year, his marginal tax rate on the last dollar he earns will be __________ % and his average tax rate for his entire income will be _________________.

a. 50 %; 50 %

b. 50 %; less than 50 %

c. 10 %; 50 %

d. 10 %; less than 50 %