The 2nd line affirms the 1st line with an opposite or contrasting statement.
Markers include adversative conjunctions, e.g. "but," or negation, e.g. "no," "neither," "nor."
The B line states the notion of the A-
For the Lord knows the way of the righteous.
But the way of the wicked will perish.
How blessed is the man who has made the Lord his trust.
And [how blessed is the man who] has not turned to the proud nor to those who lapse into falsehood.
[all of the above is a direct quote from Module 7, BE 101, Parallelism Handout, 2]