The correct option is B 4 : 5
To find the ratio of colour filled in square area we need to find the area of square.
Blue colour is in the square with the side of 4 cm
We know that area of a square = side x side
So blue colour = 4 x 4
= 16 sq. cm
Blue and orange, both the colours are inside of 6 cm square
So area of blue + orange colour = 6 x 6
= 36 sq. cm
Orange colour = 36 – 16
= 20 sq. cm
Blue : orange = 16 : 20
= 1620 = 45