What structure is used to address an array with a variable element?

The structure used to address an array with a variable element typically follows the syntax of referencing an array at a specific index, where the index can be a calculated value or a variable. In this case, the syntax "Part[X5]" suggests that "Part" is the array name and "X5" represents an index that is dynamically calculated. This means that the index is not a fixed number, but rather a variable that can be modified or assessed based on the context in which it is used.

Using mathematical expressions to calculate an index allows for flexibility and scalability in program design, facilitating access to multiple elements efficiently based on a variable's value. This is crucial in programming, particularly in environments like Rockwell ControlLogix, where managing arrays and indexed variables can optimize operations and allow for more complex data handling.

The other options do not provide the necessary dynamic calculation of an index or simply refer to different types of data structures or array notations that do not exhibit the same flexibility as the option provided in the correct answer.