(d) 0°
Wait — checking: $\tan 2A = 3\tan A$.
At A = 0°: LHS = tan 0° = 0; RHS = 3×0 = 0. ✓
At A = 30°: LHS = tan 60° = √3; RHS = 3×(1/√3) = √3. ✓
Since option (d) 30° satisfies the equation, the answer is (d) 30°.
Substitute each option using Table 8.1 values. At A = 30°: tan 2A = tan 60° = √3 and 3 tan 30° = 3 × (1/√3) = √3. Both sides are equal, so A = 30° is correct. Examiners expect you to verify by substitution from the standard values table.