Answer:
b. is a positive statement
Step-by-step explanation:
Positive statements describes what is and not ones personal opinion or value judgements. 
An example of a positive statment is when prices increase, demand falls.
 A normative statement describes value judgement and it is not based on empirical evidence.
An example of a normative statment is the government ought to increase prices of junk food so people can eat more healthy food. 
I hope my answer helps you