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Which of the following persons cannot be claimed as the taxpayer's dependent? Assume that each of the following unmarried persons live with the taxpayer during the year. The taxpayer's 75-year-old mother who has $4,200 of gross income The taxpayer's 18-year-old daughter who has $3,200 of gross income The taxpayer's 20-year-old son who is a part-time student and has $5,200 of gross income Neither a nor c. can be claimed as the taxpayer's dependent None of the above persons can be claimed as the taxpayer's dependent