What programming structure is used to repeatedly execute code for creating multiple web server instances?

The correct choice is a loop, which is a fundamental programming structure designed specifically for repeating a block of code multiple times. In the context of creating multiple web server instances, a loop allows developers to automate the repetitive task of instantiating each server without needing to write separate code for each instance.

For example, in scripting or programming, a loop can be used to iterate over a defined range, creating a new server instance during each iteration. This approach enhances efficiency and reduces the likelihood of errors that can occur when code is manually duplicated for each instance. As a result, loops are particularly valuable in cloud computing environments where scalability is essential, allowing for the dynamic provisioning of resources based on demand.

The other options do not serve this purpose effectively. A conditional statement is used for decision-making and does not inherently repeat actions. A function call encapsulates reusable code segments but does not by itself facilitate repetition unless combined with a loop. Array initialization is focused on creating a structure to hold multiple data items but does not execute code repetitively. Thus, a loop stands out as the best choice for repeatedly executing code to create multiple instances in this scenario.