To determine a key component of declaring a type of medical treatment, we can assess the given options in the context of medical research and evidence-based practice:
A. A pseudoscience, the treatment has been supported by claims that are anteced - Pseudoscience does not constitute a valid basis for a medical treatment. Claims must be supported by reliable scientific evidence rather than mere assertions.
B. The treatment has only been observed in trials - While observation in trials is important, it is not sufficient on its own. Treatments need rigorous testing and replication of results across multiple studies.
C. The treatment has only been through one double-blind test - One double-blind test is typically insufficient to declare a treatment as valid or effective. Robust evidence usually requires multiple studies and meta-analyses.
D. The treatment has been recently developed to treat a medical condition - The recency of development does not, in itself, validate a treatment. It needs to be proven effective through rigorous research.
Given this analysis, none of the options provided fully encapsulate a key component for declaring a type of medical treatment. In general, a treatment must be supported by rigorous scientific evidence, including well-designed clinical trials and peer-reviewed research validating its efficacy and safety.