Final answer:
The most effective way to relieve a 102-degree Fahrenheit fever in a toddler is by using medications, specifically antipyretics, which lower the body temperature set point. Other methods such as applying extra layers or cool water immersion can be counterproductive and may worsen the fever.
Step-by-step explanation:
When providing nursing measures to relieve a 102-degree Fahrenheit fever in a toddler with an infection, the most effective intervention is to use medications to lower the temperature set point (A). Fevers are a result of the hypothalamus adjusting the body's temperature set point upwards, a response triggered by chemicals called endogenous pyrogens that are released into the blood when a bacterium is destroyed by phagocytic leukocytes. While fevers support the immune response by inhibiting the growth of pathogens and speeding up repair processes, high fevers can be dangerous.
Therefore, antipyretic medications are typically used to lower the set point and reduce fever. Applying extra layers of clothing (option B) would be counterproductive, as it could trap heat and potentially worsen the fever. Immersing a child in cool water (option C) could induce shivering and cause the child's temperature to rise further. A tepid sponge bath (option D) is a supportive measure that can be used to comfort the child and lower the body temperature slightly before administering antipyretics.