That’s the one. Thanks. It was the first thing that came to mind when I saw this but just couldn’t remember it.
7153 is the only lucky number on the list, or if you prefer the only odious number.
ETA: peas are the only non-herbaceous plant on the list.
My be they expect kids to notice simplest differences like
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" 9 " in one number only ,
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and the looks of cabbage compared to others .
Adults are making it too complex 
Sorry, I missed the 10-14 age range. Also scratch what I said about peas not being herbaceous, they are described as such. Given the target audience I’d go with mattomic and Apollyon’s suggestion of the potato on an above/below ground distinction.
No idea for #1
#2, Ladyfinger is the only word that doesn’t end in a vowel.
That’s all I’ve got.
The cabbage does not contain a seed. Although a potato eye isn’t quite a seed either
Without reading any responses:
A) 3197 – does not contain a 5
B) My original thought was “ladyfinger”, as that term refers to a type of dessert, not an item of produce. However, I checked Wikipedia and learned that “ladyfinger” can also refer to okra, a variety of banana, and a couple of other plants. If “okra” was meant (as I’m guessing it was), I’d say “tomato”, which is a fruit, while the other choices are vegetables.
That’s especially obvious if you do Sudoku a lot and are used to looking for “naked” or “hidden” subsets. Of course now others have posted equally plausible alternate answers so I don’t know for sure, but that’s what I immediately came up with.
Only tomatoes are put in sandwiches. Unless you’re weird and make a corned beef and cabbage sandwich, but that’d be rather soggy.