This is a test of commonsense with single/multi-choices. Complete the next sentence:

How to know when to stop breeding a female dog
Factor in the age of the dog.
There are a variety of opinions and standards as to when dogs should be retired from breeding. However, you should follow standards you are most comfortable with to protect the health of your dog.

Available choices: (I) Many kennel clubs require a dog to be 8 years or younger to register litters. Many vets suggest that dogs of normal health should be retired from breeding around 8 years old.; (II) Her gender should not change too much from gender to body building to use her for her puppies. For instance, a female dog that are getting older should avoid a male dog.; (III) If you're unsure about a breed, you should consider seeking recommendations from other breeders. This will allow you to choose a senior puppy or goat.; (IV) Female dogs can only be retired after they have had at least one one session to snuggle up with or play with some sort of game in which they exercise their body and pay attention to your dog's behavior. Adult dogs don't need to have a full ten hours in a row to breed.;
The answer is:
(I)