Jackson commenced business with $10000 that he had received as a gift from his aunt and $8000 that he had received as a loan from his father. He used some of this money to purchase a machine for $15000. He obtained a mortgage for $20 000 to purchase a workshop. 

How much was Jackson's capital? 

A. $3000 

B. $10 000 

C. $18 000 

D. $38 000