Dehydration of 3-methylhexan-3-ol forms C7H14 alkenes via E1 mechanism

Steps:

• Tertiary alcohol dehydrates to carbocation at C3: CH3CH2C+(CH3)CH2CH2CH3.
• β-hydrogens lost from C2 (CH2), C4 (CH2), or methyl on C3 (CH3).
• Loss from C2 yields 3-methylhex-2-ene with E/Z stereoisomers due to different substituents on C2 and C3.
• Loss from C4 yields 3-methylhex-3-ene with E/Z stereoisomers due to ethyl/methyl on C3 and H/ethyl on C4.
• Loss from methyl yields 3-methylidenehexane with no stereoisomers as =CH2 is symmetric.

Why C is correct:

• Exactly five isomers: two E/Z pairs (four) plus one terminal alkene, per Zaitsev's rule and stereoisomer definition for disubstituted alkenes.

Why the others are wrong:

• A: Counts only three structural isomers, ignoring E/Z stereoisomerism.
• B: Counts four, possibly two E/Z and two structures, missing the exocyclic alkene.
• D: Counts six, incorrectly assuming carbocation rearrangement adds extra products.

Final answer: C