The reaction of C6H5CH = CHCH3 with HBr produces :
C6H5CH2CH2CH2Br



As we learnt in
Markovnikov's Rule -
Negative part of the reagent attacks on that carbon of multiple bond which have less number of hydrogen atoms.
- wherein

Option 1)
C6H5CH2CH2CH2Br
This option is incorrect.
Option 2)

This option is incorrect.
Option 3)

This option is correct.
Option 4)

This option is incorrect.