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) While going B) through the report C) yesterday I find D) several factual mistakes.

Introduction:
This item targets tense consistency. The time marker "yesterday" requires a past-tense verb ("found"), not present simple ("find").

Given Data / Assumptions:

• Temporal adverbial: "yesterday".
• Matrix verb in C: "find" (present simple).
• Non-finite opener "While going through the report" is fine.

Concept / Approach:
English tense must match time reference. Completed actions in the past typically take simple past. Therefore, "yesterday I find" is wrong; it should be "yesterday I found".

Step-by-Step Solution:
1) Identify time reference: "yesterday".2) Select correct tense: simple past.3) Correct verb: "found".4) Full correction: "While going through the report yesterday, I found several factual mistakes."

Verification / Alternative check:
Past progressive variant: "While I was going through the report yesterday, I found…". Both are acceptable.

Why Other Options Are Wrong:
A–B: The introductory participial phrase is grammatical.D: Object NP is fine.

Common Pitfalls:
Maintaining present tense after a clear past-time marker.

Final Answer:
C (Write: "yesterday I found")