The correct response that led to some Northerners labeling John Brown as a martyr is:
Brown's acceptance of giving up his life for his beliefs
John Brown was viewed by some as a martyr for his willingness to sacrifice his life for the abolitionist cause, even though his raid on Harpers Ferry failed. His commitment to fighting against slavery and his willingness to die for that cause resonated with many in the North, leading to the perception of him as a martyr.