The alkene that exhibits geometrical isomerism is :

The number of stereoisomers possible for a compound of the molecular formula CH₃ - CH = CH - CH(OH) - Me is :

Arrange the carbanions, $${(C{H_3})_3}\overline C $$, $$\overline C C{l_3}$$ , $${(C{H_3})_2}\overline C H$$, $${C_6}{H_5}\overline C H{}_2$$ in order of their decreasing stability :

The electrophile, $${E^ \oplus }$$ attacks the benzene ring to generate the intermediate $$\sigma - $$complex. Of the following, which $$\sigma - $$complex is lowest energy?