Be places both before and after the conjunction’
C. the word Have shows you it is past tense but it does not end in ed so it is no a past participle.
I would say B. to have a thorough knowledge of grammar
Training your dog.
It is very important to train your dog. It keeps your dog's mind active, and it >help(s)< to build an understanding between you and your dog. Often owners will shout at their dogs or even punish them ,when what is needed is training.
There is an error with sentence 2 , and you would change help to helps