What is Substitutability?

• A. An ad might offer a product or service that is not exactly what the user queried for. For example, for the user query [lg fridge freezer], an ad of [samsung fridge freezer] might show up. When the ad presents a product or service that has some difference to the queried one, you will have to carefully assess how well the advertised product or service is connected to the user's original query.
• B. An ad always matches exactly what the user asked for
• C. An ad is unrelated to the query
• D. An ad for a luxury brand only

Answer: (A)

Substitutability means an ad can stand in for the exact item a user asked for by offering a closely related alternative that still fits the user's underlying need. If someone searches for an lg fridge freezer, an ad for a samsung fridge freezer is relevant because it's the same product category and serves a similar purpose; the user’s intent is satisfied even though the brand differs. The key is how well the advertised product connects to the user’s original query, not a perfect brand-for-brand match. That’s why this option is best: it recognizes that substitutable ads can still be highly relevant when they fulfill the same need. The other statements push for exact matches, claim irrelevance, or limit relevance to niche cases, which doesn’t reflect how substitutability works.