A survey was conducted on 37 people so find out the colours that they like. It was found that 20 people like red, 22 people like blue and 17 people like green. It was also found that 7 people like blue and red, 12 people like blue and green, and 9 people like red and green. Assuming that x persons like three colours, find the value of x

A) 2
B) 4
C) 6
D) 8