After ozone layer formation what change became possible in geographical expansion of life?

Correct answer: Risk to life in land areas decreased

The correct answer is option A. Stratospheric ozone absorbs much of the Sun’s harmful ultraviolet radiation. Before effective ozone protection, exposed land surfaces were more difficult environments for many organisms because ultraviolet radiation can damage living cells and genetic material. As ozone protection became significant, the radiation risk at Earth’s surface decreased, making wider occupation of terrestrial environments more feasible over evolutionary time. This does not mean that all life immediately moved onto land or that ozone alone created life; it means one important environmental barrier was reduced. Option B is impossible because the core is extremely hot and inaccessible to ordinary life. Option C is unrelated to ozone, and option D contradicts the continued existence of the atmosphere.