Identify the correct relative pronoun: 'The report, ____ was published yesterday, caused controversy.'
答案解析
**Core Concept**: Non-restrictive clauses (Grammar).
**Analysis**: Non-restrictive clauses (adding extra info) require 'which' (B) and commas.
- **A. that** is for restrictive clauses (no commas).
- **C. who** refers to people.
- **D. where** indicates place.
**Key Point**: 'Which' for non-essential clauses with commas.
**Common Mistake**: Confusing restrictive/non-restrictive clauses.
正确答案：B