ANS:B - γ-rays

Cobalt-60 is used as a source of γ-rays (gamma rays) in medical therapy and industrial radiography. Gamma rays are a form of electromagnetic radiation with high energy and short wavelengths. They are commonly used in various applications such as cancer treatment (radiotherapy) in medicine and non-destructive testing (NDT) in industrial radiography. In medical therapy, Cobalt-60 is often used in radiation therapy machines (gamma knife or gamma therapy machines) to deliver targeted doses of radiation to cancerous tumors. Gamma rays emitted by Cobalt-60 penetrate tissues deeply and can destroy cancer cells while minimizing damage to surrounding healthy tissues. In industrial radiography, Cobalt-60 sources are used to inspect welds, pipelines, and other structural components for defects without causing damage to the material. Gamma rays emitted by Cobalt-60 penetrate through materials, allowing for the detection of internal flaws or defects in industrial applications. Therefore, Cobalt-60 serves as a valuable source of gamma rays for both medical therapy and industrial radiography applications.