Self-study
Advertisement: At most jewelry stores, the person assessing the diamond is the person selling it, so you can see why an assessor might say that a diamond is of higher quality than it really is. ███ ███████ ███ ████████ ████ ██ ███ █████ ███ █████████ ██ ████████ ██████ ███████ ██ █ ████ █████ ████ ██████████ █ ███████ ████ ███ ██████
Summarize Argument
The advertisement concludes that customers can have confidence that the prices of diamonds at Gem World are fair, because all diamonds sold at Gem World are certified in writing.
Notable Assumptions
The advertisement assumes that having certification in writing makes Gem World different from other stores, where the people who assess the diamonds are also the ones who sell them. But just having written certification doesn't guarantee that Gem World doesn't also have assessors working as salespeople, nor does it necessarily guarantee fair prices. It's possible that the certificates at Gem World are written by salespeople, or that the salespeople find other reasons to raise prices. The advertisement assumes these things are not the case.
6.
The reasoning in the advertisement █████ ██ ████ ████████████ ██ █████ ███ ██ ███ █████████ ████ █████
a
Many jewelry stores █████ ████ ███ █████ ████ ███████ ███████ █████████████ ██ ███ ███████ ██ █████ █████████
This doesn't affect the argument. The advertisement only says that Gem World offers written certification and therefore fair prices, not that it is the only store that offers these things. This claim could still be true even if many other stores offer written certification.
b
The certifications of ████████ ██ ███ █████ ███ ███████ ██ ██████ ████ █████ ██ ██████████ ██ ██████████ █████
This is a tempting answer choice. But just because someone has years of experience assessing gems doesn't mean they can't work in sales for Gem World, and so, by the advertisement's logic, be tempted to say a diamond is higher quality than it actually is. To strengthen the argument, we would want an answer choice that tells us this is not the case.
c
The diamonds sold ██ ███ █████ ███ █████████ ██ ██████ ███████ ████ █████ ████ ██ █████ ███████ ███████
This doesn't matter. What we want to know is whether Gem World offers fair prices on diamonds, regardless of how high-quality they are.
d
The diamond market ██ ██ ████████ ████ ██████ ██ ███ ████ █████████ ████████ ███ ██████ ██ ████████ ██ ███████ ████ ███ ███ ██ ███ █████
We're not interested in specific prices, let alone the specific prices for the most expensive diamonds. We want to know if the prices offered at Gem World are fair given the diamonds' quality.
e
The written certifications ██ ████████ ██ ███ █████ ███ ████████ ██ ██ ███████████ ███████ ██ ███ ████████████
This answer choice tells us that the people appraising the diamonds are independent, and not working in sales for Gem World. This makes it clear that Gem World is different from most other jewelry stores, and strengthens the argument that they offer fairer prices.