https://7sage.com/lessons/logical-reasoning/necessary-assumption-questions/na-lesson-1-pt64-s3-q12

Would someone correct my conditional logic steps that may lead to the condition that forms the answer:

Premise 1: "some gardening books published by Garden Path recommend tilling the soil and adding compost before starting a new garden on a site"

(domain) gardening books:

published by GPP <-s-> tilling AND compost (1)

Premise 2: "they (those same books) do not explain the difference between hot and cold composting."

published by GPP <-s-> / diff H&C composting (2)

Premise 3: "any gardening book that recommends adding compost is flawed if it does not explain at least the basics of composting"

(domain) gardening books :

/ basics composting -> flawed (3)

Conclusion: "some books published by Garden Path are flawed."

published by GPP <-s-> flawed (4)

(4) is the same as :

flawed <-s-> published by GPP (5)

combining (5) and (2)

flawed <-s-> published by GPP <-s-> / diff H&C composting (6)

based off of (6)

flawed <-s-> / diff H&C composting (7)

Combine (7) and (3)

/ basics composting ->/ diff H&C composting

contrapositive:

diff H&C composting -> basics composting

Based on the above D should be the answer perhaps?

Though certainly there is a flaw in there somewhere particularly with the <s> relationships inference etc.