Answer: Ally Dawson's babysitter
Step-by-step explanation:
The appositive in the sentence:
Last summer, Ally Dawson's babysitter Erin taught us how to make ice cream from scratch.
Is "Ally Dawson's babysitter"
An appositive phrase is a noun phrase that describes or renames the noun that is right next to it.
The appositive phrase always appears beside (before or after) the noun they are renaming.
From the sentence above, "Ally Dawson's babysitter" is the appositive phrase describing and renaming the noun "Erin".
Typically, an appositive can be removed from a sentence and the sentence would still make so much sense.
Removing the appositive from the sentence above, we would have:
"Last summer, Erin taught us how to make ice cream from scratch."
Which is still a perfect sentence.
So, an appositive generally provides more information about the noun next to it.