(a) Front yard. No front yard is required for any building in the "C-1" Retail Business District.
(b) Side yard. No side yard is required for any building in the "C-1" Retail Business District, except where a lot sides on any residential district, in which case there shall be a 15 foot side yard.
(c) Rear yard. No rear yard is required for any building in the "C-1" Retail Business District, except where a lot abuts on a residential district, in which case there shall be a 15 foot rear yard.