The correct way to extract mouse peritoneal fluid is ( ).
选项：

A:To open only the abdominal skin and not the peritoneum, push abdominal viscera from the outside in and to extract the peritoneal fluid from the gap in the abdominal cavity with a syringe.;
B: To open the abdominal skin and peritoneum and to aspirate the peritoneal fluid from the abdominal cavity with a glue head dropper.;
C:Not to open the abdominal skin and peritoneum and insert the syringe directly into the abdominal cavity for aspiration.;
D:To open the abdominal skin and peritoneum and to aspirate the peritoneal fluid from the abdominal cavity with a syringe.