Answer:
Change "gallops" to "gallop"
Explanation:
Horses is plural, so your verb, gallop, can not end in "s"
Horses from the various ranches of the valley gallop in the pasture.
If your subject in singular, then your verb would have to end in "s"
The horse from the various ranches of the valley gallops in the pasture.
Answer:
B. change gallops to gallop
C. change sail to sails
B. change are to is