How would you define the following rhyme scheme from this stanza taken from the epic poem, cacey's revenge:

a dismal groan in chorus came – a scowl was on each face –
when casey walked up, bat in hand, and slowly took his place;
his bloodshot eyes in fury gleamed; his teeth were clinched in hate;
he gave his cap a vicious hook and pounded on the plate.

a, b, a, b
a, b, c, a
a, a, b, b
a, c, b, c