Economies of scale account for what part of a long$-$run average total cost curve?

A$)$ Upward$-$sloping

B$)$ Vertical

C$)$ Downward$-$sloping

D$)$ Horizontal

If fixed costs are $$960,$ variable costs are $$1,440,$ and output is $12,$ then average total cost equals:

A$)$ $$100.$

B$)$ $$80.$