To answer this question, the user needs to have knowledge of common web application attacks and their impact on web services.

Now, let's go through each option and explain whether it is right or wrong:

A. SQL Injection: This type of attack targets the database layer of the application and is not specific to web service interfaces. However, if a web service is accessing a database and is not properly secured against SQL injection attacks, then the web service can be compromised. Therefore, SQL injection can be a threat to web services but is not specific to them.

B. Denial of Service: This type of attack floods the target with traffic or requests, making it unavailable to legitimate users. Web services are often targeted by denial of service attacks because they are critical components of many applications. Therefore, denial of service attacks are a threat to web services.

C. XML Injection: This type of attack exploits vulnerabilities in the way XML data is processed by an application. Although web services often use XML to exchange data, XML injection is not specific to web services. However, if a web service is not properly secured against XML injection attacks, then it can be compromised. Therefore, XML injection can be a threat to web services but is not specific to them.

D. All of the above: This option is correct because all of the attacks listed (SQL injection, denial of service, and XML injection) can be a threat to web services. Web service interfaces are exposed to the same attacks as other web applications and must be secured accordingly.

The Answer is: D