In 1986, National Geographic magazine conducted a survey of its readers' abilities to detect odors. About 7% of Caucasians in the United States could not smell the odor of musk. If both parents could not smell musk, then none of their children were able to smell it. On the other hand, two parents who could smell musk generally had children who could smell it too, but a few of the children in those families were unable to smell it. Assuming that a single pair of alleles governs this trait, is the ability to smell musk best explained as an example of a dominant or recessive trait.