Which is a complete sentence?

a. Unfortunately, four of the plates are chipped.

b. Sometimes have gooey brownies.

c. While Bryson fished in the creek.

d. Nearly all the dogs barking at me.

A. Unfortunately, four of the plates are chipped.

Any complete sentence needs a subject (person doing the action) and a predicate (the action being done)

Sentence B doesn't have a subject (who has the brownies?) so it's not a sentence.

All of these seem to have this, but there's something wrong with a lot of them.

"While Bryson fished in the creek."

This sentence leaves you hanging. While Bryson fished in the creek ... what?

"Nearly all the dogs barking at me."

"Barking" doesn't work here. It could be one of these two:

"Nearly all the dogs are barking at me" or "Nearly all the dogs barking at me are small."

Either way, as it stands now, this sentence is incomplete.

The only complete sentence here is A) Unfortunately, four of the plates are chipped.