The correct answer is: A. client
The client is the front end in cloud computing. It is the user interface that allows users to access and interact with the cloud-based services. The client can be a web application, a mobile application, or a desktop application.
The cloud is the back end in cloud computing. It is the infrastructure that provides the services that are accessed by the client. The cloud can be a public cloud, a private cloud, or a hybrid cloud.
The software is the middleware that sits between the client and the cloud. It is responsible for managing the communication between the client and the cloud, and for providing the services that are accessed by the client.
Therefore, the correct answer is: A. client.