Kai correctly used the different laws of logarithms to rewrite log27 - log(3/5) -log 5 as one logarithm.

his work is shown here

step one: log27-(log3- log5) -log 5

step two: log (3^3) -log 3+ log 5- log 5

step three: log (3^3) - log3

step 4: 3 log3- log 3

step 5: 2 log 3

step 6: log (3^2)

step 7: log 9

in which step(s) did kai apply the difference law for logarithms

a- step 3

b- step 5

c- step 4

d- step 1