Let us assume, ∠ A = x^o and ∠ B = y^o

∴ ∠ A = 3 ∠ B = (3y)^o

We know that, sum of all sides of the triangle is equal to 180^o

∴ ∠ A + ∠ B + ∠ C = 180^o

x + y + 3y = 180^o

x + 4y = 180^o (i)

Also we have, ∠ C = 2 (∠ A + ∠ B)

3y = 2 (x + y)

2x – y = 0 (ii)

Now, by multiplying (ii) by 4 we get:

8x – 4y = 0 (iii)

And adding (i) and (iii), we get

9x = 180^o

x = 20

Putting the value of x in (i), we get

20 + 4y = 180

4y = 180 – 20

4y = 160

y = 40

∴ ∠ B = y = 40^o

Hence, option B is correct