Keith McPherson Earned $20,000 Last Year as a Carpenter

Keith McPherson earned $20,000 last year as a carpenter.He paid $6,000 for food,rent,medical expenses,and other "necessities." There was little construction work in February,so he took a trip to the Caribbean and spent $4,000.What was Keith's discretionary income last year?

A) $4,000
B) $20,000
C) $10,000
D) $12,000
E) Insufficient information