Which one amongst the following are good oxidising agents?
(a) Sm$$^{2+}$$
(b) Ce$$^{2+}$$
(c) Ce$$^{4+}$$
(d) Tb$$^{4+}$$
Choose the most appropriate answer from the options below:

Good oxidizing agents are species that readily get reduced (gain electrons).

(a) Sm²⁺: Samarium in +2 state can be oxidized to the more stable +3 state. So Sm²⁺ is a reducing agent, not an oxidizing agent.

(b) Ce²⁺: Cerium in +2 state can be oxidized to more stable +3 or +4 state. So Ce²⁺ is a reducing agent.

(c) Ce⁴⁺: Cerium in +4 state tends to get reduced to the stable +3 state. Ce⁴⁺ is a good oxidizing agent.

(d) Tb⁴⁺: Terbium in +4 state tends to get reduced to the more stable +3 state. Tb⁴⁺ is a good oxidizing agent.

The good oxidizing agents are C and D.

The correct answer is Option 4: C and D only.