4. The fixed cost per unit will...

Remain constant.

Increase as activity decreases, and will decrease as activity increases.

Increase as activity increases.

Decrease as activity remains constant.

Decrease as activity decreases.

5. As activity increases, unit variable cost...

Increases by a fixed amount.

Increases proportionately with activity.

Decreases by a fixed amount.

Decreases proportionately with activity.

Remain constant.