Based on the Results of a Conservation of Number Experiment

Based on the results of a conservation of number experiment, Piaget concluded that:

A) Many adults find mathematics difficult
B) We are born with some understanding of numbers, that is, we have some kind of innate numerical sense
C) Children who are only a few months old seem to understand addition and subtraction
D) Children have no sense of numbers and numerical relations until they are about 7 years old
E) Understanding numbers is achieved with the development of formal operations