獸醫普通疾病學題庫下載題庫

所以答案應該是A嗎?
https://www.dairyherd.com/article/milk-fever

Any cow with a total blood calcium concentration of 8 milligrams per deciliter (mg/dl) or less is considered to be hypocalcemic. Cows generally don't start showing clinical signs of milk fever until the blood calcium level drops to 5 mg/dl, and often don't become downer cows until it reaches 3 mg/dl.