Final answer:
The correct option is b. Dosimeter. A badge used for monitoring personal radiation exposure is known as a dosimeter, which is one of the various devices like Geiger counters and scintillators used to measure radiation.
Step-by-step explanation:
A badge for monitoring the radiation exposure of personnel is called a dosimeter. There are several devices used to measure radiation, such as Geiger counters, scintillators, and dosimeters. Of these, dosimeters are particularly used for tracking the cumulative exposure to ionizing radiation a person receives. Commonly used types of dosimeters include electronic, film badge, thermoluminescent, and quartz fiber dosimeters.
Film badge dosimeters, for instance, work by fogging up when exposed to radiation, with the amount of fogging being proportional to the radiation level, although they are less sensitive to low levels of radiation. More advanced dosimeters use crystals that respond to radioactivity more accurately by registering emissions over time.