Final answer:
The word 'series' is used in the sentence to refer to a set of successive, similar items.
Step-by-step explanation:
The word 'series' is used in the sentence to refer to 'a set of successive, similar items'. In this context, the speaker is referring to a set of different tactics the person tried to persuade the toddler. Each of these tactics can be considered as a successive, similar item in the series of tactics.
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