An improvement in production technology causes an increase in:
A. the quantity supplied by firms and an increase in market supply.
B. supply by firms and an increase in the market quantity supplied.
C. the quantity supplied by firms and an increase in the market quantity supplied.
D. supply by firms and an increase in market supply.
If the marginal costs of 1, 2, and 3 hours of talking on the phone are $50, $75, and $105
respectively, then the total costs are of 1, 2 and 3 hours of talking on the phone are:
A. $50, $150, and $315 respectively.
B. $50, $41.67, and $115 respectively.
C. $50, $125, and $230 respectively.
D. $50, $175, and $405 respectively.