b. allusion
c. personification
Answer:
Conservation
Explanation:
Jean Piaget's theory of conservation(in psychology) implies an individual's ability to think logically that assists him/her to decide that the quantity remains the same regardless of the container it is put in or its shape or size. Piaget's theory of conservation assists to observe the development of a child's understanding across different ages. Thus, the researcher in the given situation is testing Emilia's grasp of conservation, i.e. her logical thinking ability to understand things. Hence, the answer is 'conservation'.