Emmy observed the toddlers as they filled and emptied bottles of water into the tub. Which domain of development does this support?

The correct option underscores the importance of cognitive development in early childhood as demonstrated by Emmy's observation. Filling and emptying bottles of water involves a variety of cognitive tasks such as problem-solving, experimentation, and understanding cause and effect. As toddlers engage in this activity, they are exploring concepts like volume, measurement, and the properties of liquids, all of which stimulate their thinking skills.

Furthermore, this play allows children to make predictions (e.g., what will happen when they pour water out) and test their ideas through repeated actions. Such experiences promote critical thinking and are foundational to their cognitive growth, providing the groundwork for future learning in more complex areas.

While the other domains—such as approaches to learning, language development, and social development—are all important in early childhood, the primary focus of this particular activity is on cognitive skills and the development of reasoning abilities, making cognitive development the most appropriate choice.