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

Refer to the information provided in Table 8.6 below to answer the question(s) that follow.
Table 8.6 $\text {Number of}$
$\begin{array}{llllllll}\text {Earrings}&\text { TVC}&\text { MC }&\text {AVC}&\text { TFC }&\text {TC}&\text { AFC}&\text { ATC}\\\hline0 & & & & && \\1 & 10& & & & \\2 & & 5& & & &15& \\3 & & & & &55& \\4 & & &10 & & & \\5 & & & & &90&\\\hline\end{array}$


-Refer to Table 8.6. The marginal cost of the fourth unit is ________ and the average total cost of four units is ________.

A) $5; $15
B) $10; $22.50
C) $15; $17.50
D) indeterminate from the given information