Concept:A relative clause uses a pronoun like 'who', 'which', or 'that' to combine two sentences that share a common noun or subject.
Explanation:Both given sentences talk about Gandhiji.
The first says he preached peace, and the second calls him an apostle of peace.
The pronoun 'He' in the second sentence refers back to Gandhiji.
To join them with a relative clause, we replace 'He' with the relative pronoun 'who' (since Gandhiji is a person).
The relative clause should be placed directly after the noun it describes.
Using a non-restrictive relative clause (with commas) is appropriate here because it adds extra information without defining which Gandhiji.
Option C: "Gandhiji, who preached peace, is an apostle of peace." fits perfectly.
Option A omits commas, making it a restrictive clause, which implies there are multiple Gandhijis.
Options B and D use 'because', which introduces a reason clause, not a relative clause.
Therefore, only option C correctly uses a relative clause.
Answer:Gandhiji, who preached peace, is an apostle of peace.