What is a common means of communication used by Java Virtual Machines (JVMs)?

The correct answer is Remote Method Invocation (RMI) because it enables Java objects to communicate with each other across different Java Virtual Machines (JVMs), even if they are running on different hosts. RMI provides a straightforward way for developers to invoke methods on an object located in another JVM, seamlessly handling the complexities of network communication. It is specifically designed for Java and utilizes Java's serialization mechanism to transmit objects over the network, making it ideal for distributed applications that require remote communication.

The other options, while relevant in certain contexts, are not specifically tailored for Java or JVM communication in the same way. Hypertext Transfer Protocol (HTTP) is primarily used for transferring hypertext documents on the web and does not inherently provide object-oriented communication mechanisms. Simple Object Access Protocol (SOAP) and Representational State Transfer (REST) are both web service protocols that can facilitate communication across various platforms but do not function explicitly at the level of Java objects as RMI does.