One of the biggest problems in food production has always been that people have no reliable access to exact information, ____________ is often the case in China.

1. A.
   that
2. B.
   what
3. C.
   which
4. D.
   it

 One of the biggest problems in food production has always been that people have no reliable access to exact information, ____________ is often the case in China.

A. that             B. what                  C. which                D. it

One of the biggest problems in food production has always been that people have no reliable access to exact information, ____________ is often the case in China.