Final answer:
Beta hemolysis is detected by the presence of a clear zone around bacterial colonies on blood agar, indicating the complete lysis of red blood cells.
Step-by-step explanation:
The detection of beta hemolysis is best described by observing a zone of clearing around the tested organism on blood agar plates. This clearing indicates complete lysis of the red blood cells in the medium due to the hemolytic activity of the organism. The correct answer to the student's question is option C: there is a halo and a zone of clearing around the tested organism on blood agar. In contrast, alpha hemolysis would show a greenish hue as the red blood cells are only partially lysed, and gamma hemolysis would show no change in the agar around the colonies.