In what way does the pre-implantation stage affect outcomes of radiation exposure?

The pre-implantation stage is a critical period in embryonic development, typically encompassing the first few days after fertilization until the embryo implants into the uterine wall. During this stage, the embryo is particularly sensitive to environmental factors, including radiation exposure.

When radiation exposure occurs during this phase, it can interfere significantly with the processes of cell division and differentiation. One of the key impacts is the potential for total embryonic loss, where the radiation can result in non-viable embryos that are unable to implant or develop further. Alternatively, if the embryo survives the exposure, it might develop normally despite the radiation effects. This variability in outcomes—ranging from complete loss to normal development—illustrates the unique sensitivity of this developmental stage.

In contrast, the other options suggest a more limited scope of outcomes. The assertion that there are "no effects" or that it "always causes developmental disorders" overlooks the nuanced responses that can occur. Likewise, implying that exposure leads to "only birth defects" disregards the possibility of total loss. Therefore, the correct answer captures the range of possible outcomes, highlighting the significant yet unpredictable risks associated with radiation exposure during the pre-implantation stage.