The correct answer is Option 3: A.M. Khusro - Former Chairman, Union Public Service Commission.

1. T.S. Krishnamurthy: Former Chief Election Commissioner of India

T.S. Krishnamurthy is correctly matched as the former Chief Election Commissioner of India. He served as the Chief Election Commissioner from February 2004 to May 2005. During his tenure, he played a crucial role in conducting free and fair elections in India.

2. K.C. Pant: Chairman, Tenth Finance Commission of India

K.C. Pant is correctly matched as the Chairman of the Tenth Finance Commission of India. K.C. Pant was a prominent Indian politician and statesman who served as the Chairman of the Tenth Finance Commission from 1994 to 1996. The Finance Commission is a constitutional body responsible for recommending the distribution of financial resources between the central government and the states in India.

4. R.C. Lahoti: Former Chief Justice of India

R.C. Lahoti is correctly matched as the former Chief Justice of India. He served as the Chief Justice of India from June 2004 to October 2005. As the Chief Justice, R.C. Lahoti presided over several important cases and contributed to the development of Indian jurisprudence.

3. A.M. Khusro: Former Chairman, Union Public Service Commission

This option is not correctly matched. A.M. Khusro has never served as the Chairman of the Union Public Service Commission (UPSC). The UPSC is a constitutional body responsible for conducting examinations for appointments to the All India Services and Central Civil Services. The correct Chairman of the UPSC at the time of my knowledge cutoff in September 2021 was Pradeep Kumar Joshi.

In conclusion, the pair that is not correctly matched is Option 3: A.M. Khusro - Former Chairman, Union Public Service Commission.