Use the Table Below to Answer the Following Questions

Multiple Choice

Use the table below to answer the following questions.
Table 12.2.1

-Refer to Table 12.2.1,which gives the total revenue schedule and total cost schedule of a perfectly competitive firm.The marginal cost of increasing production from 4 units to 5 units is

A) $14.
B) $128.
C) $100.
D) $25.
E) $30.