The Relationship Between the Linear Attenuation Coefficient (U) and the Half-Value

The relationship between the linear attenuation coefficient (u) and the half-value layer (HVL) is given by

A) (HVL/ $\mu$ ) = 0.693.
B) ( $\mu$ ) = 0.693/HVL.
C) HVL = 0.693 $\mu$ .
D) HVL $\mu$ ² = 0.693.