The core concept here is understanding the function of a relative clause. **Core Concept:** A relative clause is an adjective clause that modifies a noun or pronoun. **Correct Answer (B):** This option accurately defines a relative clause, highlighting its modifier role and introduction by relative pronouns or adverbs (like *who, which, that, where, when, why*). **Incorrect Option Analysis:** * **A:** Defines an independent clause, not a relative clause. * **C:** Defines a noun clause, which functions as a noun, not a modifier. * **D:** Describes a prepositional phrase, which modifies another word, but is not a clause introduced by a relative word. **Key Points:** The defining characteristic of a relative clause is its function as a modifier, linking to a noun or pronoun by a relative word. **Error Prone Areas:** Students often confuse relative clauses with other types of clauses or phrases. The key to identifying a relative clause is recognizing its modifier role and the use of relative pronouns or adverbs.