Answer:
a) public void setModel(String modelName)
Explanation:
Writing methods for a class in java requires the optional access modifier (public, private or protected) followed by the return type (void, int, String etc), this is followed by the method's name and parameter list.
In the options given in the question above, only A and D come close to describing the method however option A is correct because this method is not expected to return a value when called hence return type is void