a dichotomous key uses\ninferences.\ndna sequences.\nsubjective descriptions.\nobservable characteristics.

Answer:

D. observable characteristics.

Brief Explanations:

A dichotomous key is a tool used in biology (a sub - field of Natural Science) to identify organisms. It works by presenting a series of choices based on observable traits. For example, in identifying a plant, one might first choose between having flowers or not (an observable characteristic). Inferences are conclusions drawn from evidence and not the basis of a dichotomous key. DNA sequences are more complex and not typically used in a simple dichotomous key for basic identification. Subjective descriptions are based on personal opinion, while dichotomous keys rely on objective, observable features.