24. Rose conducted an experiment to study the effect of temperature change on the heart rate of Daphnia, transparent aquatic invertebrates commonly known as water fleas. She heated three different beakers of water containing Daphnia to a different temperature: 30°C, 32°C, and 34°C. She put a drop of water from each
beaker on a slide mount and used a microscope to observe Daphnia in each sample. She counted the number of heartbeats in one minute and averaged her results.
Which of the following could be a step in a replication of this experiment?