Show the structures and give the common names of the following groups: (a) 2,2-dimethylpropyl, (b) 1,1-dimethylpropyl, (c) 4-methylpentyl, and (d) -(CH₂)₄CH₃.

Structures of alkyl groups: isopentyl, neopentyl, tert-hexyl, and butyl.

Structures of alkyl groups: isopentyl, tert-pentyl, isohexyl, and butyl.

Structures of alkyl groups: neopentyl, neopentyl, tert-hexyl, and pentyl.

Structures of alkyl groups: neopentyl, tert-pentyl, isohexyl, and n-pentyl.

Show the structures and give the common names of the following groups: (a) 2,2-dimethylpropyl, (b) 1,1-dimethylpropyl, (c) 4-methylpentyl, and (d) -(CH2)4CH3.