Atestable hypothesis could be formed from which question?
are bass more active in the daytime than at night?
when whales jump out of water, are they happy?
are red tulips prettier than tulips of other colors?
why are gerbils more popular as pets than hamsters are?

Are bass more active in the daytime than at night?

Explanation:

A testable hypothesis is one which is based upon a proposed explanation including the facts about a natural phenomena or natural event which can be tested upon by using suitable methodology.  

Among the options given, Are bass more active in the daytime than at night? is the correct one. This is because of the fact that activity of the bass can be observed and measured in the day as well as in night therefore, this will involve a scientific methodology which can be used to appropriately answer the question.