Which element is incorrect in this sentence diagram?

“the dog” should be replaced with “their owner.”
the word “until” should be replaced by “instead.”
the pronoun “their” should be replaced by “its.”
“”ran fast” should be replaced by “stopped it.”

Option C: The pronoun “their” should be replaced by “its.”

Explanation:

Possessive Pronoun is a pronoun used to refer to the object to show ownership. For example: its, ours, yours, his, hers, mine are possessive pronouns.

In a sentence dog should be referred as 'its' and not 'his' or 'their'. So, the element which is wrong is that dog is referred as his. So, Option C mentions the portion that should be corrected. We cannot write 'their owner' in place of the dog, as per Option A. It is singular noun and not plural. Ran fast should not be replaced by stopped it as per option D.