Which mathematical concept involves understanding the relationship between numbers and quantities?

The selected answer, Number Sense, is indeed the most accurate representation of the mathematical concept that involves understanding the relationship between numbers and quantities. Number sense refers to the intuitive understanding of numbers, their magnitude, relationships, and how they can be manipulated. It encompasses skills such as estimating, comparing quantities, and recognizing patterns, which are crucial for problem-solving and mathematical reasoning.

In the context of early childhood education, fostering number sense is vital as it lays the foundation for more complex mathematical concepts. Children with strong number sense are better equipped to understand operations, make connections between different mathematical ideas, and apply their knowledge in real-life situations. Thus, it serves as a critical component in building a comprehensive mathematical framework for students.

While other options like Number Theory and Numerical Literacy touch on numerical concepts, they do not specifically focus on the foundational understanding and intuitive grasp of numbers and their relationships in the same way that number sense does. Quantitative Analysis, on the other hand, generally relates to statistical methods and the interpretation of data rather than the fundamental understanding of numbers. Therefore, Number Sense is the concept that best fits the description provided in the question.