All roses are flowers. Some flowers fade quickly. Therefore, some roses what?

To complete a syllogism's conclusion you may use only what the premises actually supply: you follow the shared (middle) term from one statement into the other. A trait that appears in neither premise can never be part of the conclusion.

1. Premise 1 — "All roses are flowers" — places every rose inside the category "flowers".

2. Premise 2 — "Some flowers fade quickly" — attaches a property to that same category of flowers.

3. So the only trait the premises put on the table — and thus the only completion drawn from the statements themselves — is "fade quickly".

The other completions each introduce a trait that no premise mentions:

• Have thorns — thorns are stated nowhere in the premises.

• Are red — colour is never mentioned.

• Smell good — scent is never mentioned.

So "Therefore, some roses fade quickly" is the completion grounded in the statements. (Strictly, the fading flowers need not include roses, so this is a plausible link rather than an airtight deduction — but among the choices it is the only one the premises support, and is the intended answer.)