Answer: A. Files and B. Registry Keys
Explanation: Files are susceptible to insecure direct object reference attack.Files whether in a hard or soft copies can be highly susceptible to insecure direct object reference attack,by hacking through the internet or by tempering, detachment or copying of it for personal selfish gains.
Registry Keys if not properly secured are highly susceptible to insecure direct object reference attack,through detachment and used for personal selfish gains.