Here Poe lays his famous rational grid upon the composition of a poem of irrationality--"The Raven." For example, he states his (predetermined) scheme for rhythm and meter: "The former is trochaic--The latter is octometer acatalectic
, alternating with heptameter catalectic repeated in the refrain of the fifth verse, and terminating with a tetrameter cataletic" (Essays 21).
A homely example may be helpful here: "There once was a man from Kentucky" is an acatalectic
line, that is, without catalexis; with catalexis, we would have the similar line, "There once was a man from Vermont." As one can readily hear, it is the line without catalexis that has the "fadeout."
Candidate (a) is acatalectic, that is, the distinctive violation of FILL is lacking because all of the metrical positions have text in them.
This makes it even more marked than the trimeter since the unmarked case (acatalectic dimeter) is to have two metra to the line and no catalexis.
Such a line, we imagine, would invite immediate reparsing as six acatalectic verse feet, (HL) (HH) (LH) (HL) (HH) (LH) -- that is, as a random set of verse feet instead of a set of repeated verse feet.