Answer:
The answer: The pronoun "his" should be replaced by "its."
Step-by-step explanation:
In the sentence, "The dog ran fast until his owner stopped it," "his" should replaced by "its" since it should refer to the dog and not the owner.
Possessive Pronoun- this refers to things or objects that show ownership. Examples are: mine, ours, yours, his, hers, its and ours, etc.
The possessive pronoun "its" is used to show ownership of a non-human subject, So, this could refer to things or animals and other living things. This includes the dog.
A better sentence would be: "The dog ran fast until its owner stopped it."