Final answer:
The child constantly checking in with her mother while playing in the park aligns with Mahler's Rapprochement stage of separation-individuation.
Step-by-step explanation:
In the scenario described, where a small child in a park regularly checks to see if her mother is still there after going off to play, the child would best fit into Mahler's Rapprochement stage of separation-individuation. This stage typically occurs between the ages of 16 and 24 months and is characterized by increased independence accompanied by a necessary assurance of the presence of an attachment figure. During Rapprochement, the child may oscillate between seeking closeness to a caregiver and exploring the environment, which mirrors the behavior of the child with her mother in the park.