What foods for guinea pigs has the most vitamin c in it?

i give them tomato, celery, broccoli, corn, cucumber ( i know not to give them to much cause it's got lots of water in it) , carrot, lettuce ( not ice berg) but my 2 mine don't all like of those foods ( like one doesn't like tomato and another doesn't like cucumber and broccoli) so is there any thing with vitamin c in it and they don't really like any fruit beside tomato