Which of the following provides a significant layer of protection against gamma radiation?

Gamma radiation is highly penetrating and can pass through many materials with relative ease. To effectively shield against gamma radiation, materials need to have high atomic numbers and density, as these characteristics contribute to absorbing and scattering the radiation.

Lead and concrete are both dense materials that possess high atomic numbers, making them effective shields against gamma rays. Lead, in particular, is often used in protective aprons, walls, and containers in medical and industrial settings where radiation is present. Concrete, with its density and thickness, is commonly used in the construction of radiation protection barriers in medical facilities and nuclear reactors.

In contrast, wood, plastic, and glass do not provide substantial shielding against gamma radiation. These materials are either too lightweight or lack the atomic composition necessary to effectively attenuate gamma photons, which is why they are not reliable options for protection against this form of radiation.