(07.04 LC) Mellie is conducting a test on mold spores on bread. She uses 6 slices of bread to compare two strains of mold. She applies one strain to the left side of the bread and one strain to the right side. She flips a coin to decide which strain goes on the right side of the bread. The mold spores that appear on each side are counted and she records them in a table.

Bread Number of Spots for Strain 1 Number of Spots for Strain 2
1 30 19
2 21 17
3 15 15
4 13 12
5 6 9
6 8 4
If Mellie is to perform an appropriate t-test to determine if there is a mean difference between the number of spots per piece of bread produced by the two strains, how many degrees of freedom should she use?

a
4

b
5

c
6

d
10

e
12