Read the following extract and answer questions 1.3 - 1.5. “Illegal car imports cost the taxman as much as R8bn Kia MD Gary Scott says about 55,000 of the illegal imports slip into SA every year, more than the number of new vehicles sold every month An estimated 440,000 illegally imported, used cars are travelling regularly on SA roads, costing the exchequer up to R8bn in lost taxes and posing a major risk to road safety, Kia SA MD Gary Scott said on Tuesday. He blamed slack regulations for the fact that about 55,000 “grey” imports, as they are known, slip into SA each year. That’s more than the number of new vehicles sold every month...” The problem being illustrated in the above extract regarding the use of gross domestic product as a measure of economic performance is… 

a) Data revision

b) Economic welfare

c) Unrecorded activity

d) Non-market production