Which of the following is a couplet?

a) “but the lord seen some sinnin’, and it caused him pain.
he says, ‘stand back, i’m gonna make it rain.'”

b) “to dry one's eyes and laugh at a fall,
and, baffled, get up and begin
so the chace takes up one's life 'that's all.”

c) “i am the grass.
let me work.”

d) “spring morning marvel
lovely nameless little hill
on a sea of mist”