Which statement best describes the function of a do-while loop?

The statement that a do-while loop must be executed at least once is fundamentally correct. This is a defining characteristic of the do-while loop compared to other types of loops, such as the while loop.

In a do-while loop, the block of code contained within the loop is executed first before the condition is evaluated. This guarantees that the loop body runs a minimum of one time, regardless of whether the condition is true or false on the first evaluation. This behavior allows developers to implement scenarios where at least one execution is necessary, such as prompting a user for input and validating it afterward.

This attribute is particularly useful in cases where you want to ensure that a specific action is taken before checking any conditions that might prevent further executions in subsequent iterations. Understanding this principle is critical for writing effective loop structures in programming.