Which of the following are constitutional isomers of an alkane with a molecular formula of C₈H₁₈?

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

Answer: (D)