Final answer:
A service providing security for communications between virtual machines is typically a VPN or a VCN, which encrypts data transmissions to protect sensitive information.
Step-by-step explanation:
The service that provides security for communications between virtual machines is known as a Virtual Private Network (VPN) or, more specifically within cloud infrastructure, as a Virtual Cloud Network (VCN). These services ensure secure transmission by encapsulating and encrypting data packets sent over the network. This is beneficial in a virtualized environment where VMs may be running on shared physical hardware, and sensitive data needs protection from potential interception or eavesdropping. Such services can include software-based solutions like Secure Socket Layer (SSL) VPNs or hardware-driven solutions like firewalls with integrated VPN capabilities. Encryption protocols such as IPSec or TLS are often used to further secure the data.