Need help with this multiple choice question

Suppose a single-parent father with four children receives these welfare benefits from the government each month: $300 in cash, $100 in food stamps, and $100 in medical benefits. If the father takes a job paying $1000 per month he will lose all these benefits and will also pay $100 in income and social security taxes. His earnings from the job are consequently being taxed at an effective marginal rate of Select one: O a. 80% O b. 60% O c. 40% O d. 20%