All of the following adaptations are evolutionary adjustments made by at least one mammal, except
a) ectothermic metabolism.
b) live birth into a pouch.
c) nourishment of young with milk.
d) specialized, varied teeth in the same mouth.

Ruby is conducting an investigation. an advantage of her design is that she can use a large range of variables, with that she can not be sure that one variable is the cause of another. what kind of investigation is ruby most likely conducting?