The correct answer is: Increasing.
When the output increases in the same proportion as the increase in input, it is said to be increasing. This means that for every unit of input, there is a corresponding increase in output. For example, if you have a machine that produces 10 widgets per hour, and you increase the input by 10%, the output will increase by 10% to 11 widgets per hour.
The other options are incorrect because they do not accurately describe the relationship between input and output. Option A, constant, is incorrect because the output is not constant. Option B, average, is incorrect because the output is not an average. Option C, decreasing, is incorrect because the output is not decreasing.
I hope this explanation is helpful. Let me know if you have any other questions.