1 two kilo of apples 2 two kilos of apples 3 two kilos of apple 4 two kilo of apple The main explanation is why? The more detailed the better

1 two kilo of apples 2 two kilos of apples 3 two kilos of apple 4 two kilo of apple The main explanation is why? The more detailed the better

2 two kilos of apples
Countable nouns should be plural together with quantifiers
Uncountable nouns are plural only on quantifiers