The youngest isn't 5 yet, so it wouldn't be fair to ask him
The other one would answer all of them correctly though. That being said, some of these are "you only know, if you know" type things. If you've never seen a tomato plant, how would you know what it looks like? I call shennanigans.
( Two Hats 🎩🎩, Mon 3 Jun 2013, 14:25, archived)

you didn't discover tomato plants until you were in your 20s, did you

( manolith hooray for me, Mon 3 Jun 2013, 14:28, archived)

No, I assumed they were hatched by a larger tomato.

( Two Hats 🎩🎩, Mon 3 Jun 2013, 14:30, archived)

they're laid by tomatobirds, silly
postmediacalgaryherald.files.wordpress.com/2011/09/tomato.jpg
( manolith hooray for me, Mon 3 Jun 2013, 14:47, archived)

But surely they've seen that potatos and onions and carrots come with dirt on and tomatos and peppers don't.
It's a matter of simple deduction.
( 2 Can Chunder Word to your mums, I came to prod bums, Mon 3 Jun 2013, 14:48, archived)