Final answer:
The line that creates tension is B) "And hit against each other, Blurring to unexpected chords." due to the use of enjambment and musical dissonance it expresses.
Step-by-step explanation:
Out of the options given, B) "And hit against each other, Blurring to unexpected chords." is the one that creates tension in the poem. This uses the poetic device of enjambment, cutting across the linear reading process and causing an unexpected shift or dissonance.
It blurs the expectations and builds a musical tension which heightens the emotional response from the reader. Additionally, the physical form and structure of a poem, such as line length and the use of indentations, can significantly influence the poem's tone and meaning. In the example of Yeats' poetry, the repetition of beginnings of lines with "And" and variations in line length through the use of indentation are noted for controlling the mood and creating patterns that impact reader engagement.
The line endings and white space are especially significant, marking the pace and rhythm, guiding the reader through the emotional landscape of the poem.