Final answer:
A distant organ biopsy would best indicate that cancer has metastasized, as it shows that cancer cells have spread from the primary tumor to distant body sites, confirming the advanced stage of the disease. The correct answer is C.
Step-by-step explanation:
The question asks which type of biopsy sample would best indicate that cancer has metastasized and is circulating through the bloodstream. The correct answer is C. Distant organ biopsy. A distant organ biopsy involves examining a tissue sample from an organ that is far from the primary tumor site. Metastasis refers to cancer cells spreading from a primary tumor to distant locations within the body, and the new cancers that form in these locations are called metastases. Examples of common metastasis sites include the brain, lungs, bones, and liver. Finding cancer cells in a distant organ is a clear indicator that the cancer has spread through the bloodstream and formed metastases, which typically signifies an advanced stage of the disease with a poorer prognosis.