Why are there much higher percentages of Pakistani first-cousin marriages in Britain than in Pakistan?​

A) ​because immigration restrictions to Britain are eased when one is marrying a British citizen
B) ​because Pakistani families in Britain have not acculturated to life there and cannot create viable social alliances
C) ​because immigrants in Britain do not routinely interact with those outside of their communities and are unable to meet marriage partners
D) ​because the amount of dowry needed for a Pakistani marriage is too high for other British citizens