❅☃ The dog is barking at something in the back yard.
❅☃ Answer: C.
❅☃Present Participle.
❅☃ A present Particle is when sentences are like this:
❅☃I am thinking
❅☃I am walking
❅☃The dog is walking.
❅☃ Another way to explain them is that they are a form of a verb ending in -ing
❅☃Etc.