Identify the part (A–E) that contains a grammatical error in the sentence below. If there is no error, choose option E (No error). Sentence (split into parts): A) No sooner B) we reached there C) than it started raining D) No mistake.

Introduction:
The construction "No sooner ... than" requires subject–auxiliary inversion in the first clause. This question checks knowledge of inversion after negative adverbials.

Given Data / Assumptions:

• Initial adverbial "No sooner".
• Clause about reaching a place.
• Clause about rain beginning.

Concept / Approach:
When a negative or restrictive adverb starts a clause (e.g., "No sooner", "Hardly", "Scarcely"), use an auxiliary before the subject: "No sooner had we reached..."

Step-by-Step Solution:
1) Identify trigger: "No sooner".2) Apply inversion in first clause: "had we reached" (past perfect is idiomatic here).3) Keep "than" to introduce the second clause: "than it started raining".4) Therefore, part B is erroneous as it lacks inversion.

Verification / Alternative check:
Correct sentence: "No sooner had we reached there than it started raining."

Why Other Options Are Wrong:
A: "No sooner" correctly begins the correlative pair.C: "than it started raining" is the correct correlative completion.D: Declares no mistake but is not the target; the error is in B.

Common Pitfalls:
Using simple past without inversion after "No sooner".

Final Answer:
B (Write: "had we reached")