Read the following passage and answer the questions that follow. The Second Amendment to the U. S. Constitution, which is a frequent source of controversy in public debates, says that "a well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed." The controversy stems from the fact that some Americans feel that the Second Amendment guarantees all citizens the absolute right to own firearms, while others believe that some restrictions on gun ownership are consistent with the Second Amendment.

Which phrase from this passage demonstrates that the author is identifying a source of debate?

"shall not be infringed."
"the Second Amendment guarantees"
"The controversy stems from"
"consistent with the Second Amendment."