I. Meso compound (two same groups) + Anti- elimination → trans - Alkene
II. ( ± ) Compound (two same groups) + Anti - elimination
III. ( ± ) Compound (two different groups) (but two eliminating groups in anti-position) + Anti- elimination → trans - Alkene
IV. ( ± ) Compound (two different groups) (but two eliminating groups is syn-position) + anti- elimination