The main product of the following reaction is
:

The reaction is an acid-catalyzed dehydration of an alcohol.Protonation of $-\text{OH}$ and loss of ${\text{H}}_2\text{O}$ gives a $2^{\circ }$ carbocation: ${\text{C}}_6{\text{H}}_5{\text{CH}}_2{\text{CH}}^{+}-\text{CH}({\text{CH}}_3{)}_2$.1,2-hydride shift from the benzylic position creates a more stable benzylic carbocation: ${\text{C}}_6{\text{H}}_5{\text{CH}}^{+}-{\text{CH}}_2-\text{CH}({\text{CH}}_3{)}_2$.Loss of a proton results in a conjugated alkene: ${\text{C}}_6{\text{H}}_5\text{CH}=\text{CH}-\text{CH}({\text{CH}}_3{)}_2$.Trans isomer is more stable than cis.