Explanation

‘15% of A is double of 30% of B’ translates directly into the equation 0.15A = 2 × 0.30B. The right side simplifies to 0.60B, so 0.15A = 0.60B. Dividing both sides by 0.15B gives A/B = 0.60/0.15 = 4, meaning A is four times B — the ratio A:B is 4:1. The trap option B (2:1) comes from ignoring the word ‘double’ and equating 15% of A with 30% of B directly, which misses a factor of two. Options A and C invert or quarter the relationship. Hence the ratio is 4:1, option D.