Which of the structures shown below are constitutional isomers of an alkane with a molecular formula of C₉H₂₀?

• A. (i), (iii), (iv), (vii)
• B. (ii), (iv), (vi), (vii)
• C. (ii), (v), (vii), (viii), (ix)
• D. (i), (iii), (v), (iv), (ix)

Answer: (A)