Question

A collection of all good smartphones is

• A. a set.
• B. not a set.

Answer 1

The correct option is B not a set.

Set is a well-defined collection of objects.

In this case, we can have one person saying that a smartphone X is good but another saying it is not good. So we can't define some smartphones as good or bad.
Since they can't be well defined and grouped together, we say this collection is not a set.