You are a forester charged with increasing productivity in a South American forest newly planted with pines from Oregon. You believe that the southern forest lacks the fungal diversity needed by the North American pines and that this lack of fungi is affecting the pines' productivity, but you have no evidence to support your ideas. Which of the following would be the best approach to assess the diversity of fungi likely contributing to tree productivity in the Oregon forest?
a. Count all the plant species and multiply by 6, as David Hawksworth did when determining the ratio of fungal to plant species in England.
b. Collect all the fruiting structures (mushrooms, morels, etc.) found aboveground.
c. Do direct sequencing on representative soil samples from across the forest.
d. Expose the trees to radiolabeled carbon dioxide and then collect the soil samples with the greatest radioactivity and do direct sequencing.

Scientist: cross-sections of stalactites—calcite formations deposited on cave ceilings by seeping water—can reveal annual variations in rainfall in particular areas over hundreds and thousands of years. we often found that when—according to these cross-sections—drought occurred in a particular area, it coincided with the collapse of an ancient society in that area. i hypothesize that drought reduced agricultural productivity in these areas, thereby leaving these societies without the resources needed to handle internal stresses and external threats. which of the following, if true, would most weaken the support for the scientist's hypothesis? a. many droughts indicated in the cross-sections of stalactites do not correspond with the collapse of a society in that area. b. information from the cross-sections of stalactites alone cannot reveal the level of agricultural output in an area at a particular time. c. most of the societies that collapsed during droughts did so when internal power struggles coincided with military raids from neighboring societies. d. most of the societies that collapsed during droughts maintained large stockpiles of food and water at the time of their collapse. e. information from stalactites also suggests that the collapse of some societies coincided with periods of abnormally high rainfall.