Fossil stromatolites and microfossils are used as evidence in studies of early life on Earth. What is a disadvantage of using these rock formations in these types of studies?

A) Paleontologists have to dig deep into Earth's crust to find them.
B) Abiotic processes lead to the formation of stromatolite-like structures or objects that resemble microfossils.
C) They must be destroyed in order to obtain samples for analysis.
D) Their analysis requires expensive and inconvenient radioisotope detection.
E) They are extremely fragile when exposed to air.