Final answer:
Malware protection, which includes anti-virus software and other protective measures, is the data safeguard against security threats among the provided options.
Step-by-step explanation:
The data safeguard against security threats that is mentioned in the options provided is D) malware protection. This includes anti-virus software, anti-malware programs, and other protective measures designed to detect, prevent, and remove malicious software from computers and networks. Malware protection safeguards your data by blocking unauthorized access through viruses, worms, Trojan horses, ransomware, and other forms of malicious code that can compromise system security and lead to data loss or theft. As for the other options, application design refers to the process of creating applications with security in mind; however, it is not a safeguard in itself but rather a principle. Accountability ensures that individuals are held responsible for their actions, which may indirectly protect data. Physical security involves preventing physical access to systems and thus is also a critical element of data protection but distinct from malware protection.