A car manufacturer receives its air conditioning units from 3 different suppliers, A,B, and C. 20% of its units come from supplier A, 30% form supplier B and 50% from supplier C. It is known that 10% of the units from supplier A are defective, 8% of units from supplier B and 5% from supplier C. If a unit is selected at random and is found to be defective, what is the probability that it came from:
 

A. Supplier A
B. Supplier C