Which one is not in IUPAC system ?

1.	Which one is not in IUPAC system ?
Answer» `underset(("3-methyl-2-butanol"))(CH_(3)-underset(OH)underset(\|)(CH)-underset(CH_(3))underset(\|)(CH)-CH_(3))` SOLUTION :It should be `4-`ETHYL`-3-`methyl HEPTANE.

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