Whenever the letter 1cM 1d appears under the current monitoring period or in the cumulative columns of a personnel monitoring report, it signifies that a (an)

a. mistake has been made in recording the equivalent dose.
b. equivalent dose higher than the minimum measurable radiation quantity was recorded during that time.
c. equivalent dose below the minimum measurable radiation quantity was recorded during that time.
d. maximal equivalent dose has been exceeded during that time.

c. equivalent dose below the minimum measurable radiation quantity was recorded during that time.