Which line is an irregular line of blank verse? "He only says, 'Good fences make good neighbours.'" "If I could put a notion in his head:" "And on a day we meet to walk the line" "And set the wall between us once again."

"He only says, good fences make good neighbors." Is the answer because it has 11 syllables instead of 10 like the others.

The line which is an irregular line of blank verse is the first one - "He only says, ‘Good fences make good neighbours.’"

A blank verse is a type of a line that consists of 10 syllables, where each second syllable is stressed ( = iambic pentameter that Shakespeare always used). The second, third, and fourth line are all good examples of blank verse, whereas the first line has 11, instead of 10 syllables.