What does the Geiger-Muller (GM) counter primarily measure?

The Geiger-Muller (GM) counter is designed to detect and measure ionizing radiation in various forms, specifically alpha particles, beta particles, and gamma rays. Its primary function includes monitoring contamination and radiation levels across these types of radiation.

The GM counter operates by using a gas-filled tube that becomes ionized when radiation passes through it. This ionization leads to electrical pulses, which are counted and converted into a measurable readout. As a versatile tool, the GM counter often finds applications in environmental monitoring, health physics, and nuclear medicine practices to ensure safety when handling radioactive materials.

The abilities to measure contamination and radiation levels spanning multiple types of radiation, including alpha, beta, and gamma particles, make option C the most accurate representation of the GM counter's capabilities.