(D) Assertion (A) is false, but Reason (R) is true.
A compass needle in a strong external magnetic field aligns with that field, not necessarily north-south. Reason (R) is correct — the compass needle behaves like a freely suspended bar magnet.
The Assertion is false because a compass needle aligns with the net/dominant magnetic field at its location. Earth's field is weak; a strong external field will deflect the needle away from north-south. The Reason is true as the textbook states the compass needle is itself a small bar magnet, behaving exactly like a freely suspended bar magnet. Since A is false and R is true, option (D) is correct.