Which root word indicates the organ associated with speech and taste?

The root word that indicates the organ associated with speech and taste is "lingu/o." This root comes from the Latin word "lingua," which directly translates to "tongue." The tongue is a critical organ in the processes of both speech and taste, as it facilitates the articulation of words and hosts taste buds that detect flavor.

In contrast, the other root words provided refer to different anatomical structures: "rhin/o" pertains to the nose (related to smell), "nephr/o" refers to the kidneys (which are involved in the body's filtration and waste management processes), and "trache/o" is associated with the trachea (the windpipe that conducts air to and from the lungs). Therefore, "lingu/o" is the appropriate root for the functions specifically linked to speech and taste.