The proton has a charge of +1.
The neutron has a charge of 0.
The electron has a charge of -1. When dealing with these type of questions you have to make sure you know what you are doing because it can be kind of confusing when getting a grade higher . its all the same the teacher will not be teaching you anything wrong it would be just her way of doing it . Paying attention in class is important because you cant come to social media every time to get a answer because it might be wrong . but , you can go with your best choice and say b because thats what i think is right.