Introduction / Context:
The statement contrasts “good” (quality) with “costly” (price) and asserts that quality drives sales despite high price. For such a claim, the language presupposes the existence of a quality distinction among books, but not any particular proportion of costly books in the market.
Given Data / Assumptions:
- Claim: Good books sell even if expensive.
- Assumption I: Quality varies; some books are good, others not.
- Assumption II: Most books are costly.
Concept / Approach:
- Using the category “good book” relies on the concept of comparative quality.
- The statement makes no claim about how many books are costly; it only says price does not stop sales for good books.
Step-by-Step Solution:
Assumption I is necessary because the sentence would be vacuous if no distinction in quality existed.Assumption II is unnecessary; the truth of the claim does not depend on the prevalence of costly books.
Verification / Alternative check:
If I were false, the predicate “good” would be meaningless and the claim collapses. If II were false, the claim can still stand.
Why Other Options Are Wrong:
II / Either / Neither / Both: These either impose an irrelevant market share condition or ignore the needed quality distinction.
Common Pitfalls:
Reading a market-wide frequency assumption into a statement about a subset.
Final Answer:
Only assumption I is implicit
Discussion & Comments