The absolute age of the trilobite fossils was most likely determined by using A - VCE - SSCE Biology - Question 35 - 2014 - Paper 1

To answer this question, we need to evaluate the methods listed in the options for determining the absolute age of fossils.

• Carbon dating is effective for dating organic materials but is typically limited to younger fossils (up to about 60,000 years).
• Transition fossils are important for understanding evolutionary processes but do not provide a method for absolute dating.
• Index fossils help in relative dating by correlating rock layers but again do not provide absolute ages.
• Potassium-argon dating is a radiometric dating method that measures the decay of potassium-40 to argon-40, which is effective for dating older geological samples, including many fossils that are millions of years old.

Based on these evaluations, the most appropriate method for determining the age of trilobite fossils is D. potassium-argon dating.