The correct answer is: A. None follows
The first statement, “Some rats are cats,” means that there exists at least one rat that is also a cat. The second statement, “Some cats are dogs,” means that there exists at least one cat that is also a dog. The third statement, “No dog is cow,” means that no dog is a cow.
From these statements, we can conclude that no cow is a cat, because no cow is a dog and some cats are dogs. However, we cannot conclude that no dog is a rat, because the first statement only says that some rats are cats, not that all rats are cats. We also cannot conclude that some cats are rats, because the first statement only says that some rats are cats, not that all cats are rats.
Therefore, none of the conclusions I, II, and III follow.