Which of the following could best replace the word ‘​ecologi…

Which оf the fоllоwing could best replаce the word ‘​ecologist​’ in Pаrаgraph 5?   5. Lewis Ziska, the lead author of that study, works as a weed ecologist with the US Department of Agriculture. He told the Union of Concerned Scientists about another climate-related allergy problem: Plants use carbon dioxide to make food via photosynthesis, but extra carbon dioxide in the air leads pollen-spreading, allergy-inducing weeds to grow faster than "useful plants" like rice and wheat. "Ragweed, specifically, grew faster, flowered earlier, and produced significantly greater pollen," he said.