"What opinion would a prisoner have of gun control, compared to that of a gun owner or a gun store owner?"
This is a very odd question, isn't it. What is a prisoner; what are the conditions of prison? A prisoner is a convicted felon who is being punished by having his rights, including right to freedom, taken away. The conditions of prison make is such that some prisoners might want guns while others might be perfectly content for all of the convicted felons not to have guns. It sort of depends, doesn't it, on the individual being questioned. I would therefore assume that a prisoner's opinion on gun control (albeit irrelevant to any sane discussion) would depend on the particular prisoner being questioned. Further ask: "would a punkish felon who has been raped and abused in prison want to have a gun, or want others in prison to have a gun?"; What about the skinhead leader, or other gang leaders in prison - would they want everyone to have a gun? Who knows and what does it really matter?
A gun store owner's opinion on gun control would likely amount to a lengthy, detailed explanation of how much red tape, legal regulation, and bureaucratic scrutiny he must already comply with - all of which already falls under the topic of "gun control". And, as to individual owners, their knowledge of the myriad of laws and regulations already controlling the purchase, ownership and use of guns will range from very little to extremely knowledgeable.
You can perhaps see how the question posed by the teacher is a bad question. By bad, I mean that it is not well thought out. It seems contrived to lead to irrelevant and factless discussions on whether or not additional gun laws are needed. So, before I would even attempt to answer the question, I would first define it as I did above. Once that's done, it comes much more into focus that some parts of the question are senseless to address without making further assumptions.
P.S: I understand that many who are attempting to answer the question are assuming that prisoners are giving their opinion as to gun control
outside of prison - as if some day they will be back out of prison possibly committing crimes. I point out that the question doesn't specify this - another reason it's a bad question which requires more assumptions to be made.
Back to the fact that the OP did not know how to respond to the question. I can't blame him. How do you think your teacher would respond to the following question:
What do you think serial killers believe need to be done to improve the quality of education in our country as compared to the opinion of a teacher or student?