Final answer:
In the reaction of 1-methylcyclohexene with H3O+, the resulting functional group added to the molecule is a hydroxyl (-OH) group, forming an alcohol.
Step-by-step explanation:
The question asks which functional group(s) would be added to 1-methylcyclohexene using the reagents H3O+ (hydronium ion).
This scenario describes an electrophilic addition reaction where water (H2O) acts as the nucleophile in the presence of an acid catalyst.
The most likely product of adding water across the double bond of an alkene in acidic conditions is an alcohol.
Therefore, the correct option is b. bromine and hydroxyl. The bromine is not relevant here since it's not listed as one of the reagents.
The resulting functional group is an -OH group, or hydroxyl group. No mention of bromine being used as a reagent precludes the formation of a bromohydrin, and there is no reduction or oxidation implied to justify the formation of a ketone or alkane.