国内钻井所用控制系统多为（）型。

A、气控液

B、电控液

C、夜控液

Which of the following factors would be most important in selecting the needle length to use for a subcutaneous injection of hydromorphone hydrochloride（）

A. The diameter of the needle.

B. The amount of adipose tissue at the administration site.

C. The amount of medication to be administered.

D. The viscosity of the solution to be injected.