According to the text describing the lac operon:

• The i gene codes for the repressor of the lac operon.
• The z gene codes for beta-galactosidase (-gal).
• The y gene codes for permease, which increases permeability of the cell to -galactosides.
• The a gene encodes a transacetylase.

Matching these typically corresponds to: (a) i gene (iii) Repressor; (b) z gene (i) Beta-galactosidase; (c) a gene (iv) Transacetylase; (d) y gene (ii) Permease (or similar variations depending on column arrangement, but Option 4 represents the correct biological pairing).