The gestalt principle the child demonstrated in the question above is the "principle of closure."
This is because the principle of closure is a type of gestalt principle whereby individuals use their brain to fill the missing part of a picture or diagram after staring at them for some time. This mental filling of missing parts in a picture or diagram ensures one discerns the actual diagram or picture.
Thus, in this case, when the child sees the completed work once, there is enough visual information present, and able to complete the picture even though it is still incomplete, this action demonstrates the gestalt principle of closure.
Hence, in this case, it is concluded that the correct answer is the "principle of closure."
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