Refer to the Information Provided in Table 8 $\text {Number of}$

Refer to the information provided in Table 8.3 below to answer the question(s) that follow.
Table 8.3 $\text {Number of}$
$\begin{array}{llllllll}\text {Earrings}&\text { TVC}&\text { MC }&\text {AVC}&\text { TFC }&\text {TC}&\text { AFC}&\text { ATC}\\\hline0 & & & & && \\1 & 20& & & & \\2 & & 10& & & &30& \\3 & & & & 110&& \\4 & & &20 & & & \\5 & & & &180 &\\\hline\end{array}$

-Refer to Table 8.3. The marginal cost of the fourth unit is ________ and the average total cost of four units is ________.

A) $10; $30
B) $20; $45
C) $30; $35
D) indeterminate from the given information