Step 1: Identify the error.
The sentence “What is the time in your watch?” is grammatically incorrect. The preposition “in” is wrong here.
Step 2: Correct usage.
The correct form is: “What is the time by your watch?” or “What time is it on your watch?”
Step 3: Analyze the options.
- What: Correct usage.
- Time: Correct word.
- In: Incorrect, because the correct preposition should be “by” or “on.”
- (Watch: Correct word.
Step 4: Conclusion.
Hence, the error is in the word “in.”
Final Answer:
\[
\boxed{\text{in}}
\]