Which control structure should be used to continue accepting input numbers, adding each to a sum, until a 0 is input?

The most appropriate control structure for this scenario is the while loop. A while loop is designed to continue executing a block of code as long as a specified condition remains true. In the case presented, you want to keep accepting input numbers and adding them to a sum until the input is equal to 0.

By using a while loop, you can define a condition that checks whether the input number is not equal to 0. As long as this condition holds true, the loop will keep processing the input as well as updating the sum.

This approach is effective because it allows for an indefinite number of inputs, stopping only when the condition (input = 0) is met. Other structures like an if statement or multiple if statements would not effectively manage repeated inputs in the same way, as they typically execute their block of code only once per condition check. Similarly, a for loop is designed for a predetermined number of iterations, which does not fit the requirement of continuing indefinitely until a specific condition (input of 0) is met.

Thus, the while loop facilitates the necessary flexibility in processing input values, making it the best choice for the task at hand.