What is wrong with the argument in the passage below?

New York City's stop-and-frisk policy should be retained because it has been extremely useful in fighting crime. Under this policy, police can stop a person and frisk him or her if they merely suspect the person might have been involved in a crime. Since the policy was instituted, the crime rate has fallen precipitously-according to the official New York Police Department crime statistics, the overall drop is more than 80 percent.

Your question is incomplete because it not does not provide the options to choose from, which are the following:

It misuses a statistic to overstate the amount of crime committed in New York City.

It assumes that because one person commits a crime, others will do so as well.

It uses an incorrect appeal to the New York Police Department as an authority.

It assumes that the police policy was the cause of the drop in crime.

Answer:

It assumes that the police policy was the cause of the drop in crime.

Explanation:

In the passage, the speaker does not mention any other causes which may have lead to the reduction of crime in New York City, such as a rise in employment, education and better quality of life. As a consequence, the speaker takes for granted that the only reason for the decrease of the crime rate is the stop-and-frisk policy, which he or she believes should be continued.