The correct answer is Option (1) –David Tilman.

The scientist who found that plots with more species showed less year-to-year variation in total biomass is David Tilman.

David Tilman, an ecologist, conducted extensive research on biodiversity and ecosystem functioning. His experiments demonstrated that higher species diversity in ecological communities often contributes to greater stability and resilience against fluctuations in biomass production across different years. This phenomenon, known as the biodiversity-stability relationship, suggests that ecosystems with greater species richness tend to exhibit more consistent and stable productivity over time.Tilman found that plots with more species showed less year-to-year variation in total biomass. He also showed that in his experiments, increased diversity contributed to higher productivity.