A fossilized Homo sapiens specimen is found to be 195,000 years old. How was this age most likely determined?

A) by calculating the ratio of C-14 to C-12 in the fossilized remains
B) by calculating the ratio of rubidium to strontium in the fossilized remains
C) by calculating the ratio of potassium to argon in the rock layers above and below the fossil
D) by calculating the ratio of C-14 to C-12 in the rock layers above and below the fossil

Carbon-14 dating is effective for organic materials up to about 50,000 years old, making it unsuitable for a 195,000-year-old specimen. Rubidium-strontium dating is typically used for much older geological samples, not directly for dating fossils. Potassium-argon dating is used for dating volcanic rock and ash associated with fossils, which can indirectly provide the age of the fossils by dating the rock layers above and below them. This method is suitable for much older timeframes, including the age of 195,000 years.