What evidence must be considered when determining whether or not a trail is adaptation?

the only way you can tell if it is a adaptation is by:

Explanation:

so Basically a trait is an adaptation if it has the product of selection, and adaptive that is beneficial in the present time. which is why there is a reason that was given from the Evolutionists because even they were asked why no one was able to see the actual morphing from one species to another.