Identify the segment that contains a grammatical error.
Now its referring to the same / big lug who met his fate / thanks to David's slingshot.

Correct option is D

Option (d) contains an error.
Explanation: The error lies in the use of “its” which is a possessive pronoun. The correct word here should be “it's”, a contraction of “it is”.

The phrase "Now it’s referring..." includes the verb “referring.” That verb requires a subject and a helping verb (auxiliary).

“its” is the possessive pronoun of “it” (used to show ownership).

→ Example: The dog chased its tail.

However, in this sentence, we are not showing possession. We are making a statement about what “it” is doing now – i.e., it is referring.

Correct sentence: Now it's referring to the same...
Grammatical rule used:
Use "it's" as a contraction for "it is" or "it has". Use "its" as a possessive form of it (belonging to it).
Example: It's raining outside. / The dog wagged its tail.