What do the yellow arrows in this illustration represent?

Scientist have long study the earths climate by looking at which of the following? the earths orbit. the earths rock layers. the antarctic ice. the earths oceans.

Sampling lake water for microscopic organisms is not as easy as it sounds when you want to both count and identify species. in a given water sample, your bacteria of choice can be rare or difficult to culture, particularly given the mixture of bacteria in a biofilm. which of the following culture media would be best for growing fecal coliforms when they are relatively less abundant than other bacteria in the lake? anaerobic culture medium enrichment culture medium complex culture medium basic culture medium

Which would be the most useful source of evidence to support mcneill's contention?