Gelman (1972) Found That 3-Year-Olds Show an Ability to Conserve

Gelman (1972) found that 3-year-olds show an ability to conserve number. One criticism of studies such as Gelman's is that

A) methodological changes may bias younger children to give responses that appear to be evidence of conservation skills.
B) lower level perceptual mechanisms, rather than cognitive mechanisms of true conservation, may be responsible for the younger children's performance.
C) younger children may be sensitive to the deletion or addition of information, rather than conserving information across changes in a display.
D) All of the alternatives are correct.