Hydrocarbons: JEE Main 2025 Chemistry question

Following are the four molecules \"P\", \"Q\", \"R\" and \"S\". Which one among the four molecules will react with $\mathrm{H{-}Br_{(aq)}}$ at the fastest rate? P: 3,6-dihydro-2H-pyran (ring C=C not attached to O); Q: 3,4-dihydro-2H-pyran (C=C attached to ring O); R: 1-methylcyclohexene; S: isopropylidenecyclohexane