Caleb Teaches Economics at Yucky University and Is Paid $50,000

Multiple Choice

Caleb teaches economics at Yucky University and is paid $50,000 per year.He also provides economic forecasts for local business for which he charges $100 per hour.What type of income does Caleb have?  

A)  All of Caleb's income is salary. 
B)  Some of Caleb's income is salary and some is personal interest. 
C)  All of Caleb's income is proprietor's income. 
D)  Some of Caleb's income is salary and some is proprietor's income.