What type of malicious software attaches to executable files with the goal of replication?

The correct choice is a virus, which is a type of malicious software specifically designed to attach itself to executable files. Once an executable file containing a virus is run, the virus can replicate itself by modifying other files and programs within the system. This replication mechanism allows the virus to spread, potentially infecting entire networks or systems without user intervention. Viruses typically require a host application to propagate, unlike other forms of malware such as worms, which can spread independently across networks. Understanding the characteristics of viruses is crucial for recognizing how they operate and for implementing effective cybersecurity measures to prevent their spread.