Which statement about tissue weighting factors w_T is true?

Which statement about tissue weighting factors w_T is true?

• A. They weight the equivalent dose in each tissue to reflect varying radiosensitivity; sum gives the effective dose.
• B. They are used to convert activity to dose directly.
• C. They are constant for all tissues and used only for external exposure.
• D. They determine the energy of emitted radiation.

Answer: (A)