III.A.7.     Assume that a specific location on the surface of the body has received an x-ray exposure of 5 roentgens.     In order to determine the absorbed dose at that point it will be necessary to know the:

    a.     Mass of the organ or tissue involved.

    b.     Spectral characteristics of the radiation.

    c.     Depth below the surface.

    d.     Type of tissue.