The child cried, "I want to do it _____________."

The correct choice, "myself," is used in this context as a reflexive pronoun to emphasize that the child wants to do the action independently. The phrase "I want to do it myself" implies that the child desires to take personal responsibility for the task, indicating a level of autonomy and a wish to handle it without assistance from others.

Using "myself" not only conveys this emphasis on individuality but also maintains the grammatical structure required in this sentence. Reflexive pronouns like "myself" are appropriate when the subject and the object of the sentence refer to the same entity.

The other options do not fit grammatically or contextually:

• "Mine" is a possessive pronoun and does not indicate the desire for independent action.
• "Me" is an objective pronoun, which would be inappropriate in this setting as it also fails to reflect that personal emphasis or autonomy.
• "Me self" is not a standard English construction and does not conform to proper grammatical usage in this context.

Therefore, "myself" is the most suitable answer, highlighting the child's intent to engage actively in the activity.