Which of the following is a major hallmark of the period of middle childhood ?

The correct answer is Development of logical thought that is concrete in nature.

Middle childhood (typically ranging from ages 6 to 11 years) corresponds to Jean Piaget's Concrete Operational Stage of cognitive development.

During this stage, children begin to think logically about concrete events and objects. They develop key cognitive skills such as conservation, classification, and seriation, allowing them to solve concrete problems systematically. However, their logical reasoning is tied directly to real, physical objects and experiences rather than hypothetical or abstract concepts.

Let's briefly evaluate the other choices:
- Emergence of make-believe play is characteristic of early childhood (Preoperational stage).
- Rapid development of motor skills and overall physical growth is most prominent during infancy and early childhood.
- Development of scientific reasoning and ability to think abstractly occurs later during adolescence in the Formal Operational stage.