SOAR (Security Orchestration, Automation, and Response) is designed to automate repetitive security tasks, orchestrate workflows, and reduce manual effort in identifying and containing threats. CompTIA Security+ SY0-701 describes SOAR as an advanced tool that integrates with SIEM, EDR, firewalls, and ticketing systems to automate detection, enrichment, and response actions.
By using SOAR playbooks, security teams can automate:
Initial threat triage
Log correlation
Host isolation
Indicator lookups
Ticket creation and escalation
This significantly reduces the number of manual steps an analyst must perform, achieving the manager's goal of streamlining threat-handling procedures.
A SIEM (B) centralizes logs and alerts but still requires manual investigation unless paired with SOAR.
DMARC (C) protects email domains from spoofing but does not automate threat response. NIDS (D) detects threats on the network but does not automate containment.
SOAR's ability to automate identification and response makes A the correct answer.

Mitigate is the risk management strategy that involves reducing the likelihood or impact of a risk. If a legacy application is critical to business operations and there are preventative controls that are not yet implemented, the enterprise should adopt the mitigate strategy first to address the existing vulnerabilities and gaps in the application. This could involve applying patches, updates, or configuration changes to the application, or adding additional layers of security controls around the application. Accept, transfer, and avoid are other risk management strategies, but they are not the best options for this scenario. Accept means acknowledging the risk and accepting the consequences without taking any action. Transfer means shifting the risk to a third party, such as an insurance company or a vendor. Avoid means eliminating the risk by removing the source or changing the process. These strategies may not be feasible or desirable for a legacy application that is critical to business operations and has no preventative controls in place. References: CompTIA Security+ Study Guide: Exam SY0-701, 9th Edition, page 1221; A Risk-Based Framework for Legacy System Migration and Deprecation2

A buffer overflow is a vulnerability that occurs when an application writes more data to a memory buffer than it can hold, causing the excess data to overwrite adjacent memory locations. A register is a small storage area in the CPU that holds temporary data or instructions. An attacker can exploit a buffer overflow to overwrite a register with a malicious address that points to a shellcode, which is a piece of code that gives the attacker control over the system. By doing so, the attacker can bypass the normal execution flow of the application and execute arbitrary commands.
References: CompTIA Security+ SY0-701 Certification Study Guide, Chapter 2: Threats, Attacks, and Vulnerabilities, Section 2.3: Application Attacks, Page 76 1; Buffer Overflows - CompTIA Security+ SY0-
701 - 2.3 2

A host-based firewall is a software application that runs on an individual endpoint and filters the incoming and outgoing network traffic based on a set of rules. A host-based firewall can help to mitigate the threat posed by suspicious connections between internal endpoints by blocking or allowing the traffic based on the source, destination, port, protocol, or application. A host-based firewall is different from a web application firewall, which is a type of firewall that protects web applications from common web-based attacks, such as SQL injection, cross-site scripting, and session hijacking. A host-based firewall is also different from an access control list, which is a list of rules that control the access to network resources, such as files, folders, printers, or routers. A host-based firewall is also different from an application allow list, which is a list of applications that are authorized to run on an endpoint, preventing unauthorized or malicious applications from executing. References: CompTIA Security+ Study Guide: Exam SY0-701, 9th Edition, page 254

A tabletop exercise is a discussion-based simulation in which stakeholders review and talk through their roles, responsibilities, and actions in response to a hypothetical incident. This allows participants to evaluate and improve response plans without actual disruption.
Reference:
CompTIA Security+ SY0-701 Official Study Guide, Domain 5.6: "Tabletop exercises involve key stakeholders discussing roles, responsibilities, and actions in response to simulated incidents." Exam Objectives 5.6: "Given a scenario, implement security incident management processes."