Why are the large UK supermarket chains diversifying? （）.

Why are the large UK supermarket chains diversifying? （）.
A.Because the retail food market in the UK has been occupied
B.foreign companies.B.Because the retail food market in the UK is saturated.
C.Because the retail food market in the UK is quite small.
D.Because diversification into new markets can promote the growth of the retail food market in the UK.
正确答案：B