Final answer:
Blood samples, fossilized bones, and plant leaves could have originated from living sources, compared to metal ores which are inorganic. Ancient microbial mats are the earliest fossil evidence for life in 3.5 billion-year-old rocks, resembling living microbial mats of today.
Step-by-step explanation:
Among the given options, blood samples, fossilized bones, and plant leaves could have originated from living sources. Blood is a connective tissue that circulates in the bodies of animals, plant leaves are part of living plants, and fossilized bones are the remains of once-living organisms that have been preserved over geological time. Metal ores, in contrast, are naturally occurring inorganic substances that are mined and processed to extract the metals they contain.
The earliest fossil evidence for life found in a 3.5 billion year old rock are microbial mats, indicating that c. The fossil superficially resembles living microbial mats that exist today is the correct answer. Scientists study fossils to understand the evolution of life, and the fossil record, though incomplete, provides crucial information on life's history on Earth.