The correct statements from the following are :
(A) $$Tl^{3+}$$ is a powerful oxidising agent
(B) $$Al^{3+}$$ does not get reduced easily
(C) Both $$Al^{3+}$$ and $$Tl^{3+}$$ are very stable in solution
(D) $$Tl^+$$ is more stable than $$Tl^{3+}$$
(E) $$Al^{3+}$$ and $$Tl^+$$ are highly stable

The elements of Group 13 show two common oxidation states: $$+3$$ (using all three valence electrons) and $$+1$$ (arising from the inert-pair effect, where the $$ns^2$$ electrons remain non-bonding).
Down the group, the inert-pair effect becomes stronger, so the stability trend is

$$\text{for }M = B,\,Al,\,Ga,\,In,\,Tl:\qquad \text{Stability of }(+3) \text{ decreases while stability of }(+1) \text{ increases}.$$

Applying this to aluminium and thallium:

• Aluminium ($$Z=13$$) lies near the top of the group, so the inert-pair effect is weak. Hence $$Al^{3+}$$ is highly stable and does not reduce (gain electrons) easily.
• Thallium ($$Z=81$$) is at the bottom, where the inert-pair effect is very strong. Therefore $$Tl^{+}$$ is far more stable than $$Tl^{3+}$$. Because $$Tl^{3+}$$ tends to gain two electrons and change to the more stable $$Tl^{+}$$ state, $$Tl^{3+}$$ behaves as a powerful oxidising agent.

Now judge each given statement:

Statement (A) $$Tl^{3+}$$ is a powerful oxidising agent.
Reason: $$Tl^{3+} + 2e^- \rightarrow Tl^{+}$$ is highly favoured. Statement (A) is correct.

Statement (B) $$Al^{3+}$$ does not get reduced easily.
Reason: $$Al^{3+}$$ is already the most stable state for aluminium. Statement (B) is correct.

Statement (C) Both $$Al^{3+}$$ and $$Tl^{3+}$$ are very stable in solution.
We have just seen that $$Tl^{3+}$$ is not very stable; it readily converts to $$Tl^{+}$$. Statement (C) is incorrect.

Statement (D) $$Tl^{+}$$ is more stable than $$Tl^{3+}$$.
Matches the inert-pair effect trend. Statement (D) is correct.

Statement (E) $$Al^{3+}$$ and $$Tl^{+}$$ are highly stable.
Both ions correspond to the preferred oxidation state of their respective elements. Statement (E) is correct.

The correct set of statements is (A), (B), (D) and (E).
Hence the answer is Option B.