An example of a parallel choice on a dichotomous key is? a)brown hair or black hair b)happy or sad c)old or young

C)old or young

A dichotomous key is a tool or a used assessment that is utilized by most scientists like biologist and ecologist to organize and classify organisms into sets of classifiable structures like trees, animals, birds, cats, dogs. These are broad descriptions that systematizes a whole family of species into a set category or a whole kingdom in a simple language such as plants or animals. 

Idont know but good luck; )

The correct answer is b