‘To’ is okay, but ‘for’ would make more sense.
“What are you going to bring to the potluck dinner” could imply that something other than food is being brought (but lots of English speakers would use it anyway).
“What are you going to bring for the potluck dinner” clearly indicates that the person asking the question wants to know what they will bring as part of the dinner.
Yes, there is indeed an error in the test sentence. As has already been mentioned, adding either ‘to’ or ‘for’ would be possible ways to repair the sentence.
By the way, the capitalization of the word ‘I’ was missing in your post, Adamant.
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[size=75]“The computer can’t tell you the emotional story. It can give you the exact mathematical design, but what’s missing is the eyebrows.” ~ Frank Zappa[/size]
A taco is a Mexican dish consisting of a fried, crisp tortilla, usually folded and filled with various mixtures, such as seasoned meat, beans, lettuce, and tomatoes (and often topped with cheese)