The correct answer is (b), Section 20.
Section 20 of the Indian Evidence Act deals with the admissibility of evidence of previous statements of witnesses. It states that such evidence is admissible in civil cases, but not in criminal cases.
Section 19 deals with the admissibility of evidence of dying declarations. It states that such evidence is admissible in both civil and criminal cases.
Section 21 deals with the admissibility of evidence of judgments of courts. It states that such evidence is admissible in both civil and criminal cases.
Section 23 deals with the admissibility of evidence of public documents. It states that such evidence is admissible in both civil and criminal cases.
In conclusion, Section 20 of the Indian Evidence Act deals only with civil matters.