I am a PhD student. I thought about 4 main top interesting objectives in my area. I also have done 3 of them totally alone. I have two main supervisors. They only give me a very general comment and feedback such as the English language (they ask me to edit my writing). They also asked me to increase the number of observation of my data. Sometimes they asked me to do something which is not accepted in my topic. I mean it is wrong. I then discuss that with them. I have done the first paper. I did all the computation, Literature review, main idea of my paper, result and everything in the paper.
Now one of my supervisors asked me to join him as a co-author. He said that due to his feedback and comment.!! I sware his comments are very very general.
Is that acceptable? Must I include him as a co-author? Did he have a right to be a co-author in my paper?
Please help me?