The correct answer is A. Overwriting multiple times. Overwriting is a method of securely erasing data from a hard disk by replacing the existing data with random or meaningless data, making it difficult or impossible to recover the original data1. Overwriting multiple times, also known as multiple-pass overwriting, is a more effective way of disposing of sensitive data than overwriting once, as it reduces the possibility of residual traces of data that could be recovered by advanced techniques2. Overwriting multiple times can be done by using specialized software tools that follow certain standards or algorithms, such as the US Department of Defense's DoD 5220.22-M or the Gutmann method3.

Parallel processing is a system implementation approach that involves running the new system and the old system simultaneously for a period of time until the new system is verified and accepted. The primary advantage of parallel processing is that it provides assurance that the new system meets performance requirements and produces the same or better results as the old system. Parallel processing also minimizes the risk of system failure and data loss, as the old system can be used as a backup or fallback option in case of any problems with the new system.

If an IS auditor finds that management did not address a prior period audit finding, the next course of action should be to interview management to determine why the finding was not addressed, as this would help to understand the root cause, the impact, and the risk level of the issue. Noting the exception in a new report, recommending alternative solutions, or conducting a risk assessment are possible subsequent steps, but they should not precede interviewing management. References: CISA Review Manual (Digital Version), Chapter
1, Section 1.6

The type of firewall that provides the greatest degree of control against hacker intrusion is an application level gateway. A firewall is a device or software that filters or blocks network traffic based on predefined rules or policies. A firewall can help protect an information system or network from unauthorized access or attack by hackers or other malicious entities. An application level gateway is a type of firewall that operates at the application layer of the network model (layer 7), which is where user applications communicate with each other over the network. An application level gateway provides the greatest degree of control against hacker intrusion, by inspecting and analyzing the content and context of each network packet at the application level, such as protocols, commands, requests, responses, etc., and allowing or denying access based on specific criteria or conditions. An application level gateway can also perform additional functions such as authentication, encryption, caching, logging, etc., to enhance the security and performance of network traffic.
A circuit gateway is a type of firewall that operates at the transport layer of the network model (layer 4), which is where data are transferred between end points over the network. A circuit gateway provides a moderate degree of control against hacker intrusion by establishing a secure connection between two end points (such as client and server) and relaying network packets between them without inspecting or analyzing their content. A circuit gateway can also perform functions such as encryption, authentication, or address translation to improve the security and privacy of network traffic. A packet filtering router is a type of firewall that operates at the network layer of the network model (layer 3), which is where data are routed between different networks or subnets. A packet filtering router provides a low degree of control against hacker intrusion by examining the header of each network packet and allowing or denying access based on basic criteria such as source address, destination address, port number, protocol, etc. A packet filtering router can also perform functions such as routing, forwarding, or address translation to optimize the delivery and efficiency of network traffic. A screening router is a type of firewall that operates at the network layer of the network model (layer 3), which is where data are routed between different networks or subnets. A screening router provides a low degree of control against hacker intrusion by examining the header of each network packet and allowing or denying access based on basic criteria such as source address, destination address, port number, protocol, etc. A screening router can also perform functions such as routing, forwarding, or address translation to optimize the delivery and efficiency of network traffic.