The correct answer is option 3: 6 years, or till they attain 65 years of age. This means that the term of office for the members of the UPSC is either for a period of 6 years or until they reach the age of 65, whichever comes first. It is important to note that the UPSC, also known as the Union Public Service Commission, is a constitutional body responsible for conducting examinations and selecting candidates for various civil services positions in the Indian government. The members of the UPSC are appointed by the President of India, and their term of office is determined by the age limit or a fixed tenure of 6 years, depending on which comes first.