针对下面句子关于style的改写，哪个是正确的？ There isn’t very much research on the use of oil palm shell as coarse aggregate in the production of concrete.
选项：

A:Little research has been conducted on the use of oil palm shell s coarse aggregate in the production of concrete.
B:The use of oil palm shell as coarse aggregate for concrete is under-researched.
C:There isn't plenty of research on the use of oil palm shell as coarse aggregate in the production of concrete.
D:There is only a little research on the use of oil palm shell as coarse aggregate in the production of concrete.