计算CT值的公式是根据（）The formula of CT value is based on（）

A.水的质量衰减系数Mass attenuation coefficient of water

B.水的线性衰减系数Linear attenuation coefficient of water

C.水的电子密度Electron density of water

D.水的密度Water density

E.空气的质量衰减系数Mass attenuation coefficient of air

正确答案：水的线性衰减系数Linear attenuation coefficient of water