A particle which is experiencing a force, is given by `F=3hati - 12hatj`, undergoes a displacement of `d=4hati`. If the particle had a kinetic energy of `3hatJ` at the beginning of the displacement, what is its kinetic energy at the end of the displacement ?
Options:
(a) `9 J`
(b) `15J`
(c) `12J`
(d) `10J`