Faulty Subject
The selection of the food was chosen by the customer.
Is there Faulty Subject?
Yes (Selection)
Stacy knocked on the door.
Is there faulty subject?
No.
What is Faulty Subject?
When the subject does not logically flow with the verb in the sentence
The dog are barking loudly in the backyard.
Fix the Faulty Subject.
The dog is barking loudly in the backyard.
The kitten, which was very small, are annoying.
Fix the Faulty Subject.
The kitten, which is very small, is annoying.