d. All of the above. 9.Doctor Neubauer, who was in charge of the identical children study, did research on: a. Unknown number. b. 2 sets of identicals. C. 4 sets of identicals. d. 6 sets of identicals.

The correct answer is b. 2 sets of identicals.<br /><br />In the identical children study conducted by Doctor Neubauer, he researched on 2 sets of identical twins. This study aimed to investigate the similarities and differences between identical twins in various aspects, such as physical characteristics, behavior, and intelligence.