NOTE: Unbreakable - means impossible to break.
Option A - 'Can be broken' is incorrect as it means breakable. Thus option A is incorrect.
Option C - 'Can be breakable' is incorrect as it is used for the things that are possible to break. Thus option C is incorrect.
Option D - 'Can be able to break' is grammatically incorrect. Also, it doesn't mean impossible to break. Thus option D is incorrect.
Option B - 'Can't be broken' means impossible to break. Thus option B is the correct answer.
'If something is unbreakable, it can't be broken.'