The answer is: B) The Government's role is to create legislation to prevent fraud
It benefits both parties when they engage in a voluntary and non fraudulent exchange, that way both parties know what they're offering and receiving, following all the guidelines to prevent fraud.
However as is the case in many of these exchanges, not all of these parties follow the extent of the law and commit fraud to ease their operation or gain a large benefit in doing so, this is when the government has to step in and do what's in its power to prevent fraud, this results in legislation being passed to prevent such acts.