Given that, Income: $5\%P = 15\%Q \implies 5P = 15Q \implies \boxed{P = 3Q}$
And, Income : $10\%Q = 20\%R \implies 10Q =20R \implies \boxed{Q = 2R}$
The income of $R = ₹2000,$ now the income of $Q = 2 \times 2000 = ₹ 4000,$ and income of $P = 3 \times 4000 = ₹12000.$
So, the correct answer is $(B).$