As Fungi Play Important Roles in Ecosystem Processes as Decomposers

As fungi play important roles in ecosystem processes as decomposers and symbiont partners, scientists are interested in understanding how global climate change may affect fungal diversity. In 2007-2008, scientists visited the maritime Antarctic, an area of the Southern Hemisphere that is noted to be warming the fastest, to conduct a survey of fungal diversity along a climatic gradient (the most prevalent weather conditions of a region along an incline) . Twenty-nine soil samples were taken along the gradient. Fungal diversity was measured in operational taxonomic units (OTUs) ; one OTU = one cluster, or group, of organisms. Here is a portion of the data collected:
Source: Newsham, K. K., Hopkins, D. W., Carvalhais, L. C., Fretwell, P. T., Rushton, S. P., O'Donnell, A. G., & Dennis, P. G. (n.d.) . Relationship between soil fungal diversity and temperature in the maritime Antarctic. Nature Climate Change, 6, 182-186.
-Each dot on the figure represents a soil sample. Which of the following is an accurate conclusion about the data presented?

A) Soil fungal diversity is greatest in warmer climates.
B) Soil fungal diversity is lowest in warmer climates.
C) Soil fungal diversity is unrelated to temperature.
D) Additional soil samples are needed at lower temperatures to better understand fungal diversity.