Problem: In an A-B-A design, a therapist uses behavioral skills training to teach a child to tie shoelaces (Phase B). When the treatment is removed (Phase A), the child continues tying independently. Which conclusion is most appropriate? Group of answer choices The design is invalid because reversals must always occur. Confounding variables explain the persistence of tying behavior. The acquired skill persists because natural reinforcers now maintain it. The child never learned the skill. Need Assignment Help?