In an experiment on how drinking dark beverages affects tooth color, red wine, cola, coffee, and tea are tested. in doing so, the researchers gathered people of the same age and gender into groups for testing. by making sure that each group had people of the same age and gender, the researchers were

running a controlled experiment.

Explanation:

In an experiment on how drinking dark beverages affects tooth color, red wine, cola, coffee, and tea are tested. In doing so, the researchers gathered people of the same age and gender into groups for testing. By making sure that each group had people of the same age and gender, the researchers were running a controlled experiment.

A controlled experiment is the one which is carefully curated by the scientists. The chosen participants are set in a controlled environment and are observed closely, as per this experiment.

ne pare rău, dar când mi-am căutat întrebarea, doar avioanele au apărut .. deci, ar putea fi răspunsul, sau ar putea fi baloane cu aer cald, deoarece acestea pot conta și ca ambarcațiunile de aer, dar nu sunt complet sigur de asta. a fost doar o presupunere, sper că am ajutat, îmi pare rău dacă nu am făcut-o. de asemenea, folosesc traducerea google, pentru a traduce ceea ce spun în engleză, așa că îmi pare rău dacă gramatica sau chiar limba nu este corectă