What is the IUPAC name of following compound?

What is the IUPAC name of following compound?
  1. 1-Bromo-1,2-dimethylbut-2-ene
  2. 4-Bromo-3-methylpent-2-ene
  3. ${ }^{+}$4-Bromo-3, 4-dimethylbut-2-ene
  4. 2-Bromo-3-methylpent-3-ene

Asked in: MHT CET 2024 (16 May Shift 1)

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