Tourism, _______ it brings in money to a country, can also result in damage to the World 

Heritage sites there.         

A. once    B. while     C. if   D. as

Tourism,    it brings in money to a country,can also result in damage to the World Heritage sites there.

Tourism,_______it brings in money to a country,can also result in damage to the World Heritage sites there.

1. A.
   because
2. B.
   as
3. C.
   while
4. D.
   since

Tourism, ______ it brings in money to a country, can also result in damage to the World Heritage sites there.

A. because                           B. as                            C. while                D. since