Answer;
C. Poor farming techniques that killed the soil were combined with drought.
Explanation;
-The Dust Bowl was caused by several economic and agricultural factors, including federal land policies, changes in regional weather, farm economics and other cultural factors.
-After the Civil War, a series of federal land acts coaxed pioneers westward by incentivizing farming in the Great Plains.
Reproductive isolating mechanisms are barriers which impeded mating (prezygotic) or prevent the hybrid from developing properly (postzygotic) but the overall effect is to cause speciation by making it difficult for two diverging species to share genes. So one kind of mechanical isolation could be the usage of contraceptives. As of temporal isolation, or behavioral isolation could be exemplified by people who suffer from diseases that cause separation (such as HIV or cancer). I hope that this is the answer that you were looking for and it has helped you.
Answer: A group of scientists wants to determine whether a relationship exists between alcohol consumption and certain types of cancer. To this end, scientists provide study participants with a questionnaire asking them how many alcoholic drinks they have per week and what diseases they have (if any). These scientists provide subjects with a similar questionnaire annually (for a decade). These scientists are performing an ASSOCIATION STUDY.
Explanation: Association study is observational study in different individuals to see if a particular behavioral pattern (such as alcohol consumption) can be associated with certain type of disease (such as cancer).
Information collected from the questionnaires distributed will be subjected to statistical analysis and conclusion(s) will be made.
