Quinn is a healthy breast-fed baby. Quinn's mother, Kelley, would like to introduce solid foods into her son's diet. What factors can help Kelley determine whether her son is physiologically ready for solid foods? Check all that apply.
(A) Quinn no longer thrusts her tongue forward and pushes out food when it is introduced.
(B) Quinn can sit up with support.
(C) Quinn is at least 4 months old.
(D) Quinn can control her own head and neck.