According to the interviewee, what is the problem with the research？A．The researchers can"

According to the interviewee, what is the problem with the research？

A．The researchers can"t explain what leads to the finding.

B．Researchers only do the tests on one kind of bacteria.

C．The research is still in the stage of controlled lab tests.

D．There are still some flaws in the procedure of the research.

请帮忙给出正确答案和分析，谢谢！