Answer:
"The lemonade labels introduced bias."
Step-by-step explanation:
By providing the labels showing the brand of each lemonade to the teenagers during the taste test, the scientist introduced a potential bias into the experiment. The knowledge of the brand may have influenced the teenagers' preferences, leading to an equal distribution of preferences between the two brands (50% for each). This bias could undermine the validity of the results because it doesn't solely reflect the intrinsic taste preferences of the lemonades but rather how branding and labeling may have affected the teenagers' choices. To obtain more reliable results, the taste test should have been conducted in a blind or double-blind manner, where the brand information is concealed from the participants.