Error Spotting – Identify the part of the sentence that contains a grammatical error (choose exactly one; select “No error” if the sentence is fully correct). Sentence: A) If the bystander had not been B) familiar with first-aid techniques C) the driver which had met D) with the accident would have died.

Introduction:
This question targets correct relative pronoun choice for persons ("who/whom") vs things ("which/that").

Given Data / Assumptions:

• Referent: "the driver" (a person).
• Relative clause begins in C with "which."
• Condition uses proper third-conditional structure elsewhere.

Concept / Approach:
For human antecedents, prefer "who/whom." "Which" is reserved for things/animals (in many styles). Thus "the driver who had met with the accident" is the appropriate wording.

Step-by-Step Solution:
1) Identify antecedent: "driver" → person.2) Replace "which" with "who."3) Full corrected sentence: "If the bystander had not been familiar with first-aid techniques, the driver who had met with the accident would have died."4) Punctuation: insert a comma after the if-clause to improve readability.

Verification / Alternative check:
Read with "who" and confirm human reference sounds natural and standard.

Why Other Options Are Wrong:

• A: Conditional past perfect in the if-clause is correct.
• B: Lexically and grammatically fine.
• D: Main clause structure is acceptable.

Common Pitfalls:
Overusing "which" regardless of antecedent; neglecting comma after long if-clauses.

Final Answer:
Option C