hello, i believe the the economic system in the society determines that.
"the three types of economic resources are also referred to as factors of production. land (including all natural resources), labor (including all human resources), capital (including all man-made resources), and when you combine all of those you get production. "
shopping mall is a group of retail stores under one roof. the cognitive structure of an urban shopping center. attributes of shopping mall image, customer satisfaction and mall patronage for selected shopping malls in southern gauteng
a is not usually thought of as an economic activity, although it could lead to one. good contacts are never to be dismissed. i'd say a is not the answer.
b with decorations. no money or services have exchanged hands. b is not the answer.
d picking up a relative at the airport. generally d is not the answer. we don't charge our relatives for services given (although if it kept them away, maybe that wouldn't be such a bad thing).
c the key word is selling. money for products. this is true economics. here's your answer.