Option 1 states that both statements are true and that Statement II is the correct explanation of Statement I. Let`s examine each statement individually to understand why option 1 is the correct answer.

Statement I states that the Rajya Sabha is not subject to dissolution and that members enjoy a tenure of six years. This is indeed true. Unlike the Lok Sabha, which is subject to dissolution every five years or in case of premature dissolution, the Rajya Sabha is a permanent body that cannot be dissolved. Members of the Rajya Sabha serve a term of six years, providing stability and continuity to the legislative process.

Statement II states that one-third of members of the Rajya Sabha retire every two years. This is also true. According to Article 83 of the Constitution of India, members of the Rajya Sabha are elected by the members of the State Legislative Assemblies. In order to ensure a rotation of members and to maintain stability in the Rajya Sabha, one-third of its members retire every two years. This staggered retirement system allows for the continuous functioning of the Rajya Sabha without the need for a complete overhaul of the membership.

Therefore, both statements are true, and Statement II provides a correct explanation for Statement I. Option 1 is the correct answer.