Which ones are the correct answers and a brief explanation

Variable cost per unit: a) increases in direct proportion to changes in the production b) decreases in direct proportion to changes in the production c) remains unchanged as the level of the production changes d) none of the above

A manufacturer plans to increase production within the relevant range of activity. What behaviour can the company expect for each of the following? Fixed cost per unit; Variable cost per unit: a) no change; no change b) no change; increase c) increase; no change d) decrease; no change