Final answer:
The true statement is that Hisashi Ouchi received a deadly level of radiation exposure during the 1999 Tokaimura nuclear accident.
Step-by-step explanation:
Based on the provided text about the true story of Hisashi Ouchi, it is clear that the correct statement is C. Hisashi Ouchi received a deadly level of radiation exposure. Ouchi was one of the victims of the 1999 Tokaimura nuclear accident, which had a significant impact on him and contributed to radiation research as scientists had the chance to study the effects of such a high dose of radiation on humans. The accident at the Tokaimura nuclear plant did not end with the successful control by the employees of the chemical mixture, which led to a criticality accident, exposing those present to high levels of radiation.