The piece of evidence that supports the argument that land plants evolved due to the presence of microbes is:
The chloroplasts of land plants, which allow them to carry out photosynthesis, is a structure similar to cyanobacteria.
This suggests that chloroplasts, which are crucial for photosynthesis in land plants, are derived from endosymbiotic cyanobacteria, illustrating a direct link between land plants and microbial life.