The correct option is 1, 2, and 3, as all three statements highlight significant advantages of thorium over uranium in nuclear energy production. Firstly, thorium is indeed more abundant in the Earth's crust, making it a more readily available resource for long-term energy strategies. Secondly, thorium-232 can generate more energy on a per unit mass basis when compared to natural uranium, especially when it is converted into fissile uranium-233 through nuclear reactions. Lastly, the waste produced by thorium reactors typically contains fewer long-lived isotopes, resulting in less harmful radioactive waste compared to that from uranium reactors. Together, these advantages position thorium as a potentially safer and more sustainable option for meeting India's future energy needs, aligning with the goals of clean energy production.