Which of the following are short-term stepwise effects of radiation exposure?

The recognition of short-term stepwise effects of radiation exposure is crucial for understanding the immediate consequences of such exposure on biological systems. The correct response highlights that primary radiochemical reactions and functional damage of cells are indeed relevant to short-term effects.

Primary radiochemical reactions occur when radiation interacts with the atoms in biological tissues, leading to the ionization or excitation of molecules. This can initiate a cascade of biochemical changes rapidly. Functional damage of cells often results from these primary reactions, as they can disrupt normal cellular functions, leading to immediate physiological problems. For instance, when DNA is damaged, it may lead to a failure in cell replication or activity, causing damage to tissues and organs.

Life-span shortening, while a significant long-term effect of radiation exposure, is not categorized as a short-term effect. It results from cumulative and chronic damage over extended periods rather than an immediate reaction to exposure. Therefore, considering the accurate classification of these effects supports the reasoning behind the correct answer.